Thou shalt not... change brands of.. motor oil

[The Fred]

Well I know that the old story about that is a big lie and story,

But I do have an interesting situation here.

A few days ago I changed the oil in my 1990 Seville (It was time at 3500 miles) and I thought hey what the heck why not try Castrol for awhile.. Well heck, less than 100 miles later, much less than that, I now have an oil leak

Before I was running Valvoline Maxlife 10/30 and I've got in there right now Castrol 5/30

Could the cause be the different weight?

I thought they were both the same at temp... but it's leaking hot and/or cold pretty darned badly too, you can leave it for a few hours and it will leak several drops of oil out of there

Where can I get the dye so that I can see where the oil is coming from?

Should I try draining the 5/30 and filling it up with some 10/30?

I'm worried that the Castrol had some stupid cleaning agent in it and destroyed a seal or two.....

[Cadillac Jim]

The first thing I would do is look at the oil filter and drain plug, because whenever you have a leak after an oil change, that's the most likely cause.

[BodybyFisher]

The 1990 calls for 10W30 if I am not mistaken, especially in hot weather

[JohnnyG]

Opinions vary wildly on what might cause this to happen. Every situation and engine are different. You must make sure there is no mechanical defect, as Jim said, then start investigating the other things. It could be just coincidence that something was just about loose enough to not leak with the Maxlife, but start to leak with the Castrol. I wouldn't be too quick to blame the oil itself, though I do agree that 5W-30 appears to be a poor chice for this car.

Other "theories" that are out there are fewer seal conditioners in some brands, allowing them to shrink back to a smaller dimension, more effective cleaning action (though I would never rely on dirt or sludge to keep my engine leak free!). And the list goes on. I have had probably 6 or 7 different oils in my N* since I've owned it, including a version of Castrol, and none of them ever leaked a drop.

[BodybyFisher]

This is what the 1993 4.9 manual states about oil viscosity. Realize that you have been stating that your local outside temperatures have been in excess of 100 degrees for weeks. As a matter of fact on August 9th you said this "107 outside today so no working on the car unless I want a heart attacl and stroke.. "

This statement below is for a 4.9, I recall the guru stating that the 4.9 was not built to excessively tight tolerances and 10W40 was ok to use, but he said that 5W30 was to light in viscosity and recommended against it. That is the 4.9, what do you have the 4.5? Pretty much similar to the 4.9 I believe. Is there a similar statement in your owners manual? While its possible that you have a leak as described above resulting from a poor oil change, its also possible that the 5W30 is so thin that it's is running right by your rings with 107 degree heat.

I can tell you this, with my 91 Seville 49 I used 5W30 Mobil 1 on a trip to Virginia Beach in 100 Degree heat with sustained 220 degree coolant temps at 70 MPH and had the OIL light come on on the highway and was 2 quarts low after 400 miles, that NEVER happened with 10W30 and NEVER happened again once the 5W30 was dumped for 10W30 dino oil.

[GreenMachine]

Was it the castrol high mileage you used or just strait GTX? The reason I ask is that Maxlife, High Mileage etc oils are thicker and have additives to prevent burn off and help seal the seals where as the standard oils have good additives but not as strong and not as thick.

[Dan]

I agree with everybody else. I think your problem has to do with viscosity, and not the brand of oil. I also don't like castrol, but not because of their quality. I just don't like they way they do business. A few years back they got in trouble for selling conventional oil that was marketed as being synthetic. They got sued by Mobil, I beleive. Castrol argued that since thier conventional oil had similar properties as synthetic, they could market it as so. I think they lost the case. On a personal note, they also don't send back my rebates :-(

[Cadillac Jim]

The name Castrol was first used when the trick racing oil was a castor oil blend, and Castrol never marketed such a blend -- but their name seemed to imply that it was a castor oil blend. So, I've been leery of them from day 1. But, their oils seem to be high quality; I never heard the story about synthetic oil fraud but if true it says someting very deep about Castrol's management.

Gues who's marketing Slik-50, the MTBE-based non-functional additive now? Blue Coral was hammered by the FTC for years and was bought by... Quaker State, who merged with Pennzoil, who separated Blue Coral and Slik-50. So, Slik-50 is now marketed by Pennzoil-Quaker State, two brands that I once thought highly of.

I'll stay with Mobil 1. There are lots of really good oils out there; most premium grades of oils like Havoline and other oil company brands are top notch, dino or synthetic.

I firmly believe that any of the oils allowed in your owners' manual are good for your car, so long as you change them regularly according to the car, your use of it, and the particular oil that you use. Which oil is your call. I use 5W-30 synthetic, but if I were in the sun belt in August and it was 100 F outside every day I would be running 10W-30 synthetic. I run synthetic because I can feel the difference in engine response over dino oil of the same grade and I believe that it keeps the engine cleaner, but that's my choice and I'm not criticizing anyone who chooses dino oil. I've driven lots of cars for lots of miles with dino oil and I know that it's good for your car so long as you keep it fresh.

[Ranger]

Speaking of oil, has anyone seen Mobil's BS commercial about their "new" oil that is the only one that can go 5000 between oil changes? It's laughable.

[The Fred]

Thanks for all of that information folks.. I put a quart of Valvoline ML 10/30 in there today and the leak is already almost gone... Good looking out about the OF and DP - I checked those first thing here

The Castrol was the higher mileage oil.. like the Maxlife is.

Always have had good luck with Valvoline in these - don't know why I tried Castrol!!!

[Dan]

I found the link about castrol selling fake synthetic oil

http://www.caranddriver.com/article.asp?se...article_id=3631

[GreenMachine]

Speaking of oil, has anyone seen Mobil's BS commercial about their "new" oil that is the only one that can go 5000 between oil changes? It's laughable.

Yeah with the police officer, fireman, etc. Clean 5000. From the looks of it its just regular dino oil if memory serves me right.

I'd be a mobil man if their stuff didn't cost twice as much. Thats what has called me to the Castrol, 5.5qt "quick fill" jug for 11-12 bucks, thats $2-2.20 a qt (GTX High Mileage anyway). Been doing good in the car too, comsumption is very minimal. Had to add maybe a quart in just over 3000 miles. (EOLI says I still have plenty of life in the oil and I promised myself to to let the run down this time ) Will be doing a lab test with Blackstone just to see how far I could have gone or if I should have changed sooner, plus will tell me if anything funky is going on inside it

[Ranger]

5.5qt "quick fill" jug for 11-12 bucks,

Yikes, I pay half that for a 5 qt jug.

[The Fred]

5.5qt "quick fill" jug for 11-12 bucks,

Yikes, I pay half that for a 5 qt jug.

Wow.. what you running in your motor..... milk?

[Cadillac Jim]

I suppose that, in the final analysis, you must use the oil rating and grade that your owners' manual recommends. The "best" oil is determined by the car, the climate at the time the oil is in use, and the way the car is being used. In the older thread about oil grade, someone posted a link for tests of several dino and synthetic oils of different grades, but I can't find it. Mobil 1 came out on top on most of the tests but there was one, with a name beginning with "A" that matched Mobil 1 in the tests.

[Ranger]

5.5qt "quick fill" jug for 11-12 bucks,

Yikes, I pay half that for a 5 qt jug.

Wow.. what you running in your motor..... milk?

Supertech conventional 10W30

[BodybyFisher]

I suppose that, in the final analysis, you must use the oil rating and grade that your owners' manual recommends. The "best" oil is determined by the car, the climate at the time the oil is in use, and the way the car is being used. In the older thread about oil grade, someone posted a link for tests of several dino and synthetic oils of different grades, but I can't find it. Mobil 1 came out on top on most of the tests but there was one, with a name beginning with "A" that matched Mobil 1 in the tests.

Here it is Jim:

http://www.micapeak.com/info/oiled.html

[JimD]

5.5qt "quick fill" jug for 11-12 bucks,

Yikes, I pay half that for a 5 qt jug.

Wow.. what you running in your motor..... milk?

Supertech conventional 10W30

Anyone know who bottles this for Wal-Mart?? I use their two cycle oil with no problems.

[Cadillac Jim]

The oil that matched or outperformed Mobil 1 in the link provided by bodybyfisher is Amsoil. Anybody use it? How much does it cost?

[latinowarrior]

Well I'm about to drop a new motor on my 84 Eldo and the oil I will be using will be Mobil 1. I've been using Mobil 1 on my Exp and I have over 200,000 miles and I change it every 5000 mil.

[Cadillac Jim]

I just checked online and found that Amsoil 5W-30 costs $6.75 to $7.00 per quart, depending on how much of it you buy. All dealer buy-online links go back to the Amsoil web site with the same prices. I think I'll stay with Mobil 1.

[The Fred]

Isn't Amsoil that oil company who claimed to have a 20,000 mile oil?

I'm not saying it isn't good stuff but I don't want to run anything for that long and I hope if someone does that they woud at least change the filter now and then ... heh

[Cadillac Jim]

Mobil 1 is supposed to be good for lots of miles, too, but I change when my oil life indicator reads 50%. That gives a good safety margin for long engine life with dino oil. For lots of short trips and such, that's about 3,000 miles.

If you drive 250 miles a day, you will do 20,000 miles in 80 days. Perhaps Amsoil would be good for vehicles that do that kind of service. I'm not sure what that has to do with me and my Cadillac, though.

[KHE]

Mobil 1 is supposed to be good for lots of miles, too, but I change when my oil life indicator reads 50%. That gives a good safety margin for long engine life with dino oil. For lots of short trips and such, that's about 3,000 miles.

If you drive 250 miles a day, you will do 20,000 miles in 80 days. Perhaps Amsoil would be good for vehicles that do that kind of service. I'm not sure what that has to do with me and my Cadillac, though.

Jim,

There is PLENTY of safety margin in the oil life monitor to run it to 0% with conventional oil and not have any problems. The guru said there was about a 2:1 safety margin in the depreciation curve - not that you'd want to run it way past 0%, but realize that when the oil life monitor states 0%, the oil will still protect the engine.

[Cadillac Jim]

There is PLENTY of safety margin in the oil life monitor to run it to 0% with conventional oil and not have any problems. The guru said there was about a 2:1 safety margin in the depreciation curve - not that you'd want to run it way past 0%, but realize that when the oil life monitor states 0%, the oil will still protect the engine.

If I did that, I would be driving 6,000 miles between oil changes with dino oil. That might not void the warranty but I put a whole lot more than 50,000 miles on my car and expect it to remain in perfect condition.

You are probably right. But, I view exploration of those possibilities as a form of destructive testing with personal property. One thing that can make longer oil changes safer is the eye-and-nose test -- if the oil looks dirty or cloudy, or smells of anything but oil, change it. Also you can test it, although I don't know of anyone who sells kits for testing engine oil for individuals to use with their own cars. The oil life indicator uses the PCM to predict the utility of the oil based on the time/temperature/stress history of the engine and can be very good, and with a 100% safety margin it is pretty sure to be safe for engines that you want to be trouble-free for 50,000 miles. This gets me back to using the oil life indicator at 50% with synthetic oil, for a about a 300% margin.

I didn't post pictures of the cams of my engine after 117,000 miles because of the thumbnail/storage issue, and it doesn't tell a profound tale that can't be put easily into text. But, it looked like a new engine.