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I recently purchased a 97 Deville. My first Caddie and I LOVE IT! It has 127k on it and was idling rough so I purchased a DIY diagnostics program and got a misfire reading on Cyl 3 so I changed out the plugs and wires. Went from 17.5 mpg to a strong 23! Love it! Anyways, when I was changing the plugs on 5 and 6 there was (to me) an excessive amount of oil on the them. The archs were dry, but the threads were soaked. The car runs like a top, I'm just wondering if this is something that my be cause for alarm. I also seem to be burning about a quart every thousand miles... but from what I hear that is common? I am not very mechanically inclined so any advice or opinions would be greatly appreciated!

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Oil on the threads of the plugs is typically a sign of a bad o-ring gasket. Along with the regular valve cover gaskets, there are individual o-rings that go around each spark plug. It's most likely nothing to be too concerned about. You have to figure that even though that amount of oil may seem excessive, it took (most likely, depending on when the plugs were last changed) tens of thousands of miles for that amount to leak onto the threads.

As for the "burning" oil, it could be a leaking oil pan gasket, leaking valve cover gasket, leaking case-half seal, or nothing leaking at all. It may be a good idea to replace your PCV valve. If the PCV system isn't working properly it can cause oil to "disappear". Mine went through a little over a quart in 1,000 miles and I don't have a leak anywhere. I changed the PCV valve and haven't lost any oil that I can tell. If the oil were actually burning, it would turn your exhaust smoke blue.

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As for the oil consumption, it needs a good whoop'in. The Northstar was designed to be run hard. The compression ring is near the top of the piston and will get caboned up frozen in the land. It needs some tender loving WOT (Wide Open Throttle). Start out in 2nd gear and plant your foot firmly on the floor. Do not release it until you reach 6000 RPM or about 70 MPH or as close as you can get comfortably and safely. Then let it back down to 50 or so. If you saw a lot of carbon dust "smoke" in the mirror, do it again. Don't worry, you won't hurt it. Do this about once a month and watch you oil usage decrease.

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  • 2 weeks later...

As for the oil consumption, it needs a good whoop'in. The Northstar was designed to be run hard. The compression ring is near the top of the piston and will get caboned up frozen in the land. It needs some tender loving WOT (Wide Open Throttle). Start out in 2nd gear and plant your foot firmly on the floor. Do not release it until you reach 6000 RPM or about 70 MPH or as close as you can get comfortably and safely. Then let it back down to 50 or so. If you saw a lot of carbon dust "smoke" in the mirror, do it again. Don't worry, you won't hurt it. Do this about once a month and watch you oil usage decrease.

Hmmm... You mean I only get to unleash that beautifully smooth beast once a month?! I'll do it next time I get out! Thanks!

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As for the oil consumption, it needs a good whoop'in. The Northstar was designed to be run hard. The compression ring is near the top of the piston and will get caboned up frozen in the land. It needs some tender loving WOT (Wide Open Throttle). Start out in 2nd gear and plant your foot firmly on the floor. Do not release it until you reach 6000 RPM or about 70 MPH or as close as you can get comfortably and safely. Then let it back down to 50 or so. If you saw a lot of carbon dust "smoke" in the mirror, do it again. Don't worry, you won't hurt it. Do this about once a month and watch you oil usage decrease.

Hmmm... You mean I only get to unleash that beautifully smooth beast once a month?! I'll do it next time I get out! Thanks!

The only thing you have to worry about hurting are the motor mounts. My car is "living" proof of that....I just had to replace one on Sunday. Check those and be sure they are in good shape first. The tranny shouldn't suffer any foul effects from WOT unless there was already something not-quite-right with it to start with.

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As for the oil consumption, it needs a good whoop'in. The Northstar was designed to be run hard. The compression ring is near the top of the piston and will get caboned up frozen in the land. It needs some tender loving WOT (Wide Open Throttle). Start out in 2nd gear and plant your foot firmly on the floor. Do not release it until you reach 6000 RPM or about 70 MPH or as close as you can get comfortably and safely. Then let it back down to 50 or so. If you saw a lot of carbon dust "smoke" in the mirror, do it again. Don't worry, you won't hurt it. Do this about once a month and watch you oil usage decrease.

Hmmm... You mean I only get to unleash that beautifully smooth beast once a month?! I'll do it next time I get out! Thanks!

I reckon that I am one of the lucky ones. :D

Mine only uses about a half quart between changes.

I change it about every 6000 miles.

My understanding is that this is fairly unusual, as most NorthStars do use some oil.

So far, I have never had to add any oil between changes.

I have 78,000 miles on it.

It does get regular WOT use. :D

I don't do the WOT PROCEDURE, exactly... (it doesn't seem to need it)... but it does get a "VERY BRISK" drive fairly regularly. :D

I love the sound (and the feel) of the N* when it is winding up. :D

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I recently purchased a 97 Deville. My first Caddie and I LOVE IT! It has 127k on it and was idling rough so I purchased a DIY diagnostics program and got a misfire reading on Cyl 3 so I changed out the plugs and wires. Went from 17.5 mpg to a strong 23! Love it! Anyways, when I was changing the plugs on 5 and 6 there was (to me) an excessive amount of oil on the them. The archs were dry, but the threads were soaked. The car runs like a top, I'm just wondering if this is something that my be cause for alarm. I also seem to be burning about a quart every thousand miles... but from what I hear that is common? I am not very mechanically inclined so any advice or opinions would be greatly appreciated!

As you probably noticed, the plugs go through the CAM covers. Each plug 'hole' in the CAM cover has a seal. Those seals can leak oil into the plug ports and that was what you are seeing. You can change the CAM seals but that is a huge job, the rear cam cover is hard to get off due to a lack of room by the firewall, and the front cam cover needs the cam pulley removed. I would just change the plugs and keep an eye on the oil level in those ports, you can use a shop vac to suck it out if the need be. The threads where soaked simply from the oil in the plug port.

A quart every 1000 miles is a little excessive, the 'normal' spec is a quart every 1500 miles. Check for leaks. DO NOT use more than 7 quarts, you can even get by with six quarts. Filling the crankcase to the FULL level is not necessary, plus it causes more probability that the case half will leak. You will get a LOW OIL message on your dash if you are 2 quarts low, you can put oil in at that point and its not a big issue

You can also do the WIDE OPEN THROTTLE (WOT) procedure as recommended above. The WOT procedure exercises and re-seats the rings, cleans the combustion chambers and improves oil consumption. It was suggested that doing the WOT procedure would hurt your engine mounts, not true, the WOT procedure when done correctly puts VERY LITTLE stress on the engine mounts you are not FLOORING the ENGINE from a STOP you are flooring it from 40 mph to 70 or so... If you need engine mounts replace them, but the WOT procedure will NOT hurt them, it will only HELP your engine

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I recently purchased a 97 Deville. My first Caddie and I LOVE IT! It has 127k on it and was idling rough so I purchased a DIY diagnostics program and got a misfire reading on Cyl 3 so I changed out the plugs and wires. Went from 17.5 mpg to a strong 23! Love it! Anyways, when I was changing the plugs on 5 and 6 there was (to me) an excessive amount of oil on the them. The archs were dry, but the threads were soaked. The car runs like a top, I'm just wondering if this is something that my be cause for alarm. I also seem to be burning about a quart every thousand miles... but from what I hear that is common? I am not very mechanically inclined so any advice or opinions would be greatly appreciated!

As you probably noticed, the plugs go through the CAM covers. Each plug 'hole' in the CAM cover has a seal. Those seals can leak oil into the plug ports and that was what you are seeing. You can change the CAM seals but that is a huge job, the rear cam cover is hard to get off due to a lack of room by the firewall, and the front cam cover needs the cam pulley removed. I would just change the plugs and keep an eye on the oil level in those ports, you can use a shop vac to suck it out if the need be. The threads where soaked simply from the oil in the plug port.

A quart every 1000 miles is a little excessive, the 'normal' spec is a quart every 1500 miles. Check for leaks. DO NOT use more than 7 quarts, you can even get by with six quarts. Filling the crankcase to the FULL level is not necessary, plus it causes more probability that the case half will leak. You will get a LOW OIL message on your dash if you are 2 quarts low, you can put oil in at that point and its not a big issue

You can also do the WIDE OPEN THROTTLE (WOT) procedure as recommended above. The WOT procedure exercises and re-seats the rings, cleans the combustion chambers and improves oil consumption. It was suggested that doing the WOT procedure would hurt your engine mounts, not true, the WOT procedure when done correctly puts VERY LITTLE stress on the engine mounts you are not FLOORING the ENGINE from a STOP you are flooring it from 40 mph to 70 or so... If you need engine mounts replace them, but the WOT procedure will NOT hurt them, it will only HELP your engine

In my case I think the motor mount got killed because it was already pretty close to dead. That's why I suggested making sure they are in good shape first. I don't believe that WOT will hurt a mount that's not already in rough shape. My mount was probably going downhill for a while, but the last time I did the WOT procedure seemed to be the straw that broke the camel's back...so to speak. That was when the clunking and "hard shifting" started to happen. I thought it had something to do with my suspension, then later I realized the mount was completely shot.

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And as far as the SeaFoam thing goes, there are a lot of different opinions on that topic. If you do a google search for Seafoam use in Northstars, some people will swear by it, while others will swear it killed their engines. If you do decide to do it, by NO means suck enough of it through a vacuum line to kill your motor, because it will literally KILL your motor. It's called Hydrolocking. Here are the instructions for using it in a vacuum line if you do decide to use it. This is taken directly from their website. http://www.seafoamsales.com/gasoline-engine-faqs.html I would personally never use it, as I prefer the plain old WOT method, but that's just my opinion.

Using Sea Foam through a vacuum line is easy and safe if you remember one thing. Liquids don’t compress and can cause an engine to hydro lock if too much liquid is applied. Always regulate the rate at which Sea Foam goes into the engine. Never insert the vacuum line into the bottle of Sea Foam, always pour Sea Foam slowly into the vacuum line.

It is important to make sure the engine is at operating temperature. Then find a vacuum line that feeds all cylinders, usually the PCV hose or the vacuum brake booster line may feed all cylinders. If you are in doubt as to which vacuum line to use, YOU MUST check with a certified auto technician.

After the correct vacuum line has been located, start engine and disconnect vacuum line. With engine at idle and at operating temperature slowly pour Sea Foam into vacuum line. It is important to control the rate at which Sea Foam goes into the vacuum line. The engine will labor while applying Sea Foam. Pour enough Sea Foam into the vacuum line to make the engine labor at idle, but not enough to stall engine.

After 1/3 to ½ can of Sea Foam has been induced into the engine, shut engine off and let sit (hot soak) for about 5 minutes and reconnect vacuum line. After the 5 minute hot soak period, restart engine in a well ventilated area as exhaust may be extreme for a short time. Road test the vehicle immediately after start up, driving aggressively until exhaust looks normal. This usually takes up to 5 miles. It is always better and safer to road test car to clean the gum, varnish and carbon out of the engine.

By doing this you have done an intense carbon cleaning procedure to your engine. This operation is recommended once a year or every 15,000 miles.

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absolutely NO need for seafoam at all I would NEVER use it EVER for a bunch of reasons. Do the WOT that is all you need to do. Lots of people talk and give misinformation with no direct experience.

Read this thread, seafoam caused bigtime leaks

http://caddyinfo.ipb...showtopic=10036

And if you screw up, this can happen very easily. This was done by a GM tech putting solvent into the throttle body, the rod blew out threw the side of the engine

Hydrolock_UEC_into_intake_with_pool.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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absolutely NO need for seafoam at all I would NEVER use it EVER for a bunch of reasons. Do the WOT that is all you need to do. Lots of people talk and give misinformation with no direct experience.

Read this thread, seafoam caused bigtime leaks

http://caddyinfo.ipb...showtopic=10036

And if you screw up, this can happen very easily. This was done by a GM tech putting solvent into the throttle body, the rod blew out threw the side of the engine

Hydrolock_UEC_into_intake_with_pool.jpg

I read through that thread, and that's pretty awful. sad.gif That's just one more reason I would personally never use the stuff, nor would I advise anyone else to use it. I've read way too many horror stories about it. I'd rather keep my car around for a while.

I only posted the instructions because I figure if he did for some reason decide to do it, it should at least be done "right", although using it in the first place isn't right in my opinion.

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Hey thanks guys! I appreciate the help! A guy from my work said I should suck enough SeaFoam through a vaccuum line until it kills the motor to clean it out. I think I would rather just put my foot down if it'll do the same thing!

Leave the snake oil on the shelf where it belongs, not in your engine.

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Ok guys!... and Ladies ;) did the WOTs like instructed (2nd gear 40 - 70) and it seems more responsive! Too early to tell if oil consumption is improved. Plus one for all you! But since I did them, sometimes I have to crank on it for 5-10 secs in the morning before it starts... 3 times now since the WOTs... and my traction control kicks in every time I make a left turn from a stop reguardless how easy I take off. minus two for me... :( Its running smooth and straight and once I get it started the first time it starts right up. Did I break something??? I should maybe add on the very first WOT (I did 3 over a 35 mile period) there was a high pitch squeak from the motor compartment when it shifted... Don't know if that would give a clue?

Edited by Floatintheboat
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Ok guys!... and Ladies wink.gif did the WOTs like instructed (2nd gear 40 - 70) and it seems more responsive! Too early to tell if oil consumption is improved. Plus one for all you! But since I did them, sometimes I have to crank on it for 5-10 secs in the morning before it starts... 3 times now since the WOTs... and my traction control kicks in every time I make a left turn from a stop reguardless how easy I take off. minus two for me... sad.gif Its running smooth and straight and once I get it started the first time it starts right up. Did I break something??? I should maybe add on the very first WOT (I did 3 over a 35 mile period) there was a high pitch squeak from the motor compartment when it shifted... Don't know if that would give a clue?

Its not likely this is related to your WOTs unless your plugs got fouled by loosened carbon, keep doing them. Another good thing is a long roadtrip at highway speeds, that cleans out everything. You will find your engine will thrive on that.

As far as the traction control check behind each front wheel the hub bearing has a sensor that is an integral part of the TC. Its either a loose connection, a short in the wiring or a bad hub bearing.

The high pitched squeel can be the serp belt or tensioner, the water pump belt or tension, the AC clutch (doubtful)

When you do WOTs you will hear noises that you had never heard before and it will highlight any weaknesses or wear. Regardless, its good for you engine as is the road trip at highway speeds mixed with WOTs

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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More WOTs! and More Driving! Got It!

That reminds me of more Cowbell...

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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there was a high pitch squeak from the motor compartment when it shifted.

That is just the belt slipping during the shift. Much like chirping your tires at a shift during a drag race.

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Its not likely this is related to your WOTs unless your plugs got fouled by loosened carbon, keep doing them.

Another good thing is a long roadtrip at highway speeds, that cleans out everything.

You will find your engine will thrive on that.

As far as the traction control check behind each front wheel the hub bearing has a sensor that is an integral part of the TC. Its either a loose connection, a short in the wiring or a bad hub bearing.

The high pitched squeel can be the serp belt or tensioner, the water pump belt or tension, the AC clutch (doubtful)

When you do WOTs you will hear noises that you had never heard before and it will highlight any weaknesses or wear. Regardless, its good for you engine as is the road trip at highway speeds mixed with WOTs

I am a firm believer in "THAT"

Mine will soon have 80,000 on it and I have never had to add oil to it, since the day I bought it brand new.

Mine does get driven pretty fast on some of my road trips.

:D :D :D :D

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More WOTs! and More Driving! Got It!

That reminds me of more Cowbell...

Haha! Needs more cowbell... I remember that. laugh.gif

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