Unusual Oil Light - Diesel

[SerratedFrond]

Greetings!
I'm new around here, I hope someone can help me.

I recently purchased an '82 rabbit diesel (4spd manual) It was sold to me with 15w40 oil in the motor, with instructions to keep it that way. The oil was over 3k miles old so I decided to get it changed. Here is where the story begins.

They swapped out the oil and filter, and replaced with 5w30. This really wouldn't be a concern (since I live in Midwest and a thinner oil would be nice for cold start), but the thinnest oil the manual recommends is 10w30.

Another reason this new oil is a concern is; ever since I got the car back the oil light will go on when the engine is at low RPM. Essentially whenever I am coasting (clutch pushed in) or stopped at a light. ALSO this only starts happening once Ive driven the car for 3 or 4 miles (warmed up)

What leads me to believe the thin oil caused this is twofold. 1. it didn't happen before it was changed
2. with the 15w40 oil the light will go on at a HIGH rpm UNTIL the car is warmed up. (the exact opposite right?)

Anyway I took the car back to get the oil changed, I had them put in 10w40. HOWEVER, the light is still coming on in the same manner. What could be the problem?!

I have a hunch they may not have changed the oil . . Because they were trying very hard to talk their way out of doing the rechange. Is there a way to test motor oil to check what type it is?

Thanks for any help! = ]

[stevethefolkie]

You should be running proper diesel lubricant in a diesel engine - standard motor oil is for gas engines. The best way to know what your engine is digesting is to change the oil and filter yourself. I ran diesels for a few years (one an early 4speed rabbit, the other a tubodiesel jetta) and always ran 15W50 - winter or summer. I also always ran diesel specific oil.

The stresses imposed by compression ignition are different than those from a 4cycle engine - I use Rotella - by the way - if you can't find it at an auto parts store I know tractor supply carries it.

[trev0rbr]

i run 5w40 shell rotella full syntheic or 15w40. depends if you wanna go synthetic or not, you just need to get diesel specific oil.

[SerratedFrond]

Thanks for the replies guys.

The manual simply says I need to use oil marked "CC". I searched my local auto supply store and couldnt find anything with that designation. I was only able to find API, SM, and SL.

I dont even know what those guys at the shop used, I certainly will be doing all my own oil changes from now on.

Regarding synthetic oil, can I safely change over to that? Do I need to blow out my oil lines or anything? Also, do synthetic oils have the same designations (ie "CC")? Or what should I look for?

[SerratedFrond]

Alrighty! Thanks guys. I was able to find the Rotella 15w40 after a bit of calling around. Ive always considered oil changes not worth my time (since I dont save hardly any money), but after this experience I will be doing them myself. Its the only way to be sure . . .

Anyway I got under the thing to change the oil, and noticed that the block heater I recently installed had started coming out! If anyone has any advice here is the thread:
http://www.vwforum.com/forum/viewtop...=251805#251805

[stevethefolkie]

I've had a couple VW Diesels (two non-turbo, one turbo) and they all (like most diesels) "loved their oil" - the added expense of synthetic never seemed worth it to me.

You don't need to blow anything out - but take care with the block heater - I lost my favorite diesel when one fell out on I83 - I didn't really notice anything wrong until there was no heat (my temp gauge was broken) - by the time I got to an exit it was a bit late for the engine - I slapped a freezer plug into the hole and filled 'er with coolant - and she did run - but she was never the same - the overheating had "clearanced" the engine -