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Rotella T interesting results


brmurph

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Last oil change I decided to try Rotella T 10w30 diesel oil (non synthetic) in my 98 deville, the results were kind of surprising.  I now burn twice the amount of oil (450 per quart compared to 900 on plain pennzoil) however I no longer see anything coming out of the exhaust at WOT ( I use to see a cloud before).   Is all this carbon now sticking to internal parts instead of blowing out?  Am I using the right Rotella that has been recommended for flat tapits?  

Thanks.

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Carbon is a by-product of combustion, Are you, or were you seeing bluish "smoke" or darker brownish "smoke" at WOT?

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Blue smoke or "light" colored smoke on hard accel or WOT is usually oil burning in the combustion chamber. Brown is usually carbon deposits and sometimes a little rich mixture but rich is usually more black. 

One quart in 450 would definitely be excessive oil consumption. GM in their wisdom stated one quart per thousand miles is acceptable. I don't like to get involved in oil viscosity or oil brand debates, however I think you should consider another oil change soon. If the problem persists, I would try freeing up the rings. There are methods and some chemicals to do that.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Interesting.  You think the intake might tell me something?  It probably has been cleaned in the last 20,000 miles or so but not sure why the intake would have anything to do with crankcase oil?  Care to elaborate??

I agree about changing back to penzoil.  Will be interesting if I can get back to 800 miles per quart.  

As far as being a coincidence, I agree burning more oil could be but nothing coming out of the tall pipe seems odd, Seems it must be going somewhere.

thanks guys.

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I am leaning towards some bound up rings where excessive blowby is entering the crankcase and creating excessive pressure causing oil mist to be blown into the intake and thus getting mostly consumed during combustion.   Usually people who overfill their crankcase experience this problem.  I know additives are not recommended by the manufacturer, but on a 20 year old car, I feel all bets are on for these solvents.  I would start by cleaning the intake and pcv, then adding Marvel Mystery oil to the crankcase when it is low.  Keep the crankcase 1/2 qt low.  At the next oil change, add Motor honey to the crankcase. I suspect if you check your intake, it'll have a thick tar like substance around the throttle body.

 

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No leaks?, strange that suddenly this would happen, what Pennzoil?, starburst SN or a high mileage blend?  Were you using any additive with the Pennzoil?, like EOS or a zddp booster?

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 wouldn't say no leaks but nothing dripping.   I was using regular 10w30 penzoil from Walmart it say Api service sn.    The Rotella says api service cj-/sm "meets api service cj-4, ci-4 plus, ci-4,, ch-4, Cg-4, cf-4, cf/sm. ..    Did I use the wrong Rotella?

no additives.

Edited by brmurph
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I'm still trying to stay away from the oil debate issue but here is something to think about:

The following was taken from an oil manufacturers website....

Diesel oil typically contains more robust detergency additives than gasoline oils
It is safe to use a diesel oil in your gasoline engine, provided the diesel oil meets the appropriate specifications and viscosity requirements of your engine. For example, if your gas engine calls for a motor oil that meets the API SN specification, you can safely use a diesel oil of the correct viscosity that meets the API SN spec. For the typical gasoline application, however, a diesel oil isn’t required and the more appropriate choice is a quality gasoline motor oil for both performance and value.

Pay attention to oil specifications

The American Petroleum Institute (API) publishes its “C” category of specification for diesel oil (currently CJ-4) and its “S” category for gasoline motor oil (currently SN). It’s common for today’s diesel engine oils to carry both the API CJ-4 and API SN specifications. Though they’re truly designed for diesel applications, they can be used in gasoline applications for motorists who want to use one oil in all applications. If the diesel oil carries both specs, the oil is safe to use in diesel and gasoline applications. If the diesel oil does not carry the “S” category, it is strongly recommended against using it in gasoline applications.

In the past, many have been told diesel oils were tougher than passenger car oils for a number of reasons, including higher viscosity, improved corrosion protection, higher Total Base Number and more. Diesel oils are often thought to be formulated with special components not available in gasoline motor oils, such as more robust detergency additives to handle the soot inherent to diesel engines. In some motorists’ minds, diesel oils are still analogous to better protection.

While that may have been true in the past, modern oils are formulated for their intended applications. While both diesel and gasoline oils contain many of the same additives to guard against wear, corrosion, foaming and more, they also contain additives designed to manage the byproducts of combustion. Some of those byproducts change, depending on whether the engine runs on gasoline or diesel fuel. If your vehicle uses a gasoline engine, it’s best to use an oil that contains the correct additives to handle the byproducts of gasoline combustion. The same holds if you’re operating a diesel engine.

Many times the engine builder will help provide insight as to what success they have found. Outside of that, if you have a bone-stock gasoline-powered application it’s best to stick with a gasoline motor oil. They are designed for that type of application and have the components required to manage that engine.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Wow so confusing :-), thanks all for the great info.   I will change back to regular Pennzoil soon and post my results.   I haven't heard anyone say that the Rotella should not be used so hopefully no permanent damage.   Certainly not trying to start the typical oil thread as I have seen many of them (which is why I wanted to try the Rotella) going back to the guru.  

Thanks again.

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I won't go into all that has been posted on Rotella there is a ton of info here about it.  

You have a 98 with rubbing element lifters, the SN spec reduced zddp to 800 ppm so you might want to add a pint of EOS to bump up the zddp to take care of your lifters.

About a year ago, I spoke to Shells tech support about Rotella and they confirmed it as at least 1200 ppm and many muscle car guys with rubbing element lifters use it.  

I doubt you did any damage but am very surprised with your results

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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