midrange

I just found out that the previous owner of the A4 we purchased was using a non synthetic 15W40 Diesel oil in our 2.8.

i'm in aww here... Never have I heard of this being used in this motor and i'm not sure what to do about it. I have always used fully synthetic in my previous Audi's.

Has anyone ever heard of this? Can I change to a non diesel oil now? What oil is suggested? Due to the fact its been ran most of its life on non synthetic, i think i'll have to stick with reg motor oil unless semi is an option. I've always been told to not change to synthetic after its been used with reg oil due to the fact that reg oil may have built up some sludge and the synthetic can break apart that sludge and have the chucks of broken down sludge go through the motor.

Thanks in advance.

mikeh

Use the search tool above to find similar threads. Here is a good place to start.

https://www.audiforum.ca/performance...ngine-oil.html

midrange

That didn't help me at all but thanks for trying..

I'm more concerned of the whole DIESEL OIL used in my NON DIESEL motor...... The fact that the car would normally use 5W30 say, and the guy used 15W40 Diesel Oil....

I just want to hear from someone who knows a lot about oil say that using diesel oil in a reg fuel car is not abad thing.. But i searched your way and have yet to find anyone thats in the same boat i am.

adamstasiak

He used correct oil. There is no such thing as Diesel oil. It has just happened that diesels run on 15W40 and this oil is used by gasoline engines as well. In the AUDI booklet it says use 15W40 all year round. I bet your engine is nice and clean inside as this oil is a really good cleaner.

Your compression ratio is 10 or 11:1 and with 5 valves per cylinder you need good lubrication.

You will wreck your engine fast on 5W30 if used during summer time or even during winter on higway driving. I say BAD IDEA.

You can use synthetic any time but do not mix dino oil with synthetic as they do not mix.

midrange

Thanks so very much. I appreciate it.. I have never owned a diesel and don't know much about them and when he told me he used diesel oil, i was a little concerned.

I admit, when i took the oil fll cap off, the internals were very clean. It has been ran on this oil since new.

adamstasiak

Your AUDI is not just an old AUDI!

In 1998 this was still brand new thing to the world to have a family-sports car and a 4 wheel drive all at once, and Audi wanted to get their place on the market by installing the engine that you have. The newer engines are not quite the same as they are toned down with exception of S4 which is still a powerhouse.

You will learn quickly about the incredible power and acceleration of your beast, once you know how to use it. Your engine combines TORQUE and POWER at the same time. This is rare achievement in terms of engines. For example take a 300 horse power Lexus. You can pass it anytime you want and the reason for it is that it's torque is not at the same RPMs as horsepower. So Lexus owner has either acceleration or power, but not both - as you do.

This comes at the expense of lubrication that must be perfect as your engine has oversized valves and there is lots of pressure on the internal parts all the time.
In the legal cases lawyers who represented owners with wrecked engines called them "OIL STARVED ENGINES", and this is true. The engine is clearly oil starved and it also relies on it for cooling. Oil is my priority when it comes to maintenance. I have 260,000 km on mine and it runs perfect.

midrange

Are you saying adamstasiak that my car is using the wrong oil? What oil do you use?

1998 was new to awd 2.8's? My 93 was a 4 door sedan AWD 2.8. Unless I am misunderstanding your post. Reason we went with another 2.8 is because our last one lasted to 400 000kms and i know these motors to be solid!

adamstasiak

No,

All I say is that you have a special engine that has lots of power and so you should be aware of the oil issue that these engines have. The oil must be on full and fresh all the time.

I use Castrol 15W40 not synthetic for 10 months and Castrol Synthetic 10W40 once a year.
It works for me.

Sorry I probably said too much as I thought it is your first AUDI.

(Now just watch how they jump on me for saying that)

midrange

lol.. no worries mate.. I just read the part that said

The engine is clearly oil starved and it also relies on it for cooling.

I thought you were saying my engine is oil starved.. Great.. thats the same oil he used.. Castrol Non Synthetic 15W40.

Thanks for your input.

trucker9

15W40 ran my cat for a million km's suffice to say that that with dual rated oils that it would seem kind of heavy for neg temp starts when 5W40 is available, but that is all and the detergents that are inherent in 15w40 as one of the previous posts stated that it should be clean as a whistle inside as you noted it was. Drive it like you stole it!