Oil questions

[tripppleP]

I know this borderlines a newbie question but I still want to ask. My car is at 80k miles and I always used regular motor oil. Is it still ok to now switch to synthetic?

I keep reading Rotella T6 is a popular choice but can I switch after all these miles?


Also, Rotella T6 synthetic says its for Diesel engines. I'm taking it that this is still ok to use in my MS3?

[Db09ms3]

Yes use it. Why haven't you been using any kind of synthetic? Don't say you're cheap. Besides you've been here long enough to know how to search.

T6 does say it's for diesels but if you read the labeling on back you'll see it meets the specs in our manuals.

[tripppleP]

Why haven't I been using synthetic? Because I was told by my dealer to never use synthetic in this car. Knowing what I know now I have no clue why I was ever told this. It pisses me off really.

[MSMS3]

Originally Posted by tripppleP Why haven't I been using synthetic? Because I was told by my dealer to never use synthetic in this car. Knowing what I know now I have no clue why I was ever told this. It pisses me off really.

Your dealer was stupid. The temperature at the bearing journals in the turbo reaches close to 1500 F. Engine oil bathes those journals. The oil has to withstand that heat. The turbo spins at over 100,000 rpm.

Regular mineral spirit motor oil does not do well in heat that high. It breaks down and leaves ash or hard “coke” deposits inside the turbo.

Any reputable dealer would tell you to run synthetic oil. I can’t imagine any car dealer telling a customer to run dinosaur - mineral spirits oil in a turbo engine of any make or model brand car or truck in the last 20 years.

Yes, run a 10w40 synthetic. It does not harm to switch. Rotella T6 was always my choice unless I could not find it. There is now a 0w40 T6, I believe. Run either with complete confidence.

T6 is very popular with us and in the subie community because we have direct injection fueling with insanely rich AFR. This leaves a lot of soot and carbon deposits. Check the inside of your exhaust pipe and note the slight (hopefully no more) black exhaust smoke when you first go wide open throttle and the injectors richen the AFR. This is “dirty”, but normal, not unlike a modern turbo diesel engine. T6 has now been relabeled because of this to also be used in cars.

Such engines benefit from stronger and different detergent additives. That’s why synthetic oils developed for modern direct injection turbodiesels are a natural choice for us.

The only contraindication is for those running very high concentrations of ethanol, like full E85/or close to it. Those fuel blends and T6 don’t work well inside the high pressure fuel pump for some reason. Those guys run a different oil. The rest of us that run T6 have excellent results from this oil.

If you can’t find T6 don’t run any other Rotella. Select a comparable weight Mobil 1 synthetic or Castrol Edge synthetic.