Quote:
Originally Posted by bmlocal175
Just saw this thread... Just got my second free oil change and the rear diff changed. First oil change was around 1000 miles and now I'm around 2500.
Looking at my receipt they gave me 88865635. I didn't know anything about this new oil. Just wondering why I received this oil and not the other. I don't track, not yet anyway, and I have had the car for 2 years and 2500 miles. I know, drive the damn thing.
Going to service the car myself from now on now the freebies are gone. Am I good with the rear diff for awhile if I don't track? Should I change to the new oil next change or keep using what they just put in?
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Getting them changed before 5000+ miles is better than nothing. 1000 isn't that late anyways. If the diff was recently changed, you're good for a long time. You could do another one if you want to.
As for oil, 88865635 is the OEM 5w30 oil, which is absolutely fine for street use. If you're never planning on tracking, you probably will never notice the difference between running 5w30 or 0w40 ESP. Because I'm mildly OCD, I probably would switch to 0w40 ESP at the next needed oil change; but, definitely don't do an oil change super short term JUST to change to the newer oil.
When a car comes into service at a dealer, all they care about is the VIN. With the VIN, they simply punch it into the system and it tells them any and every part/fluid/bolt etc. you can imagine that that VIN
came with
from the factory and therefore what it needs when whatever needs fixing/replacing. So, since 2018 ZL1's were factory filled with 5w30, that's what popped up, it told them they have it in stock, as well as the filter, and boom, job done, RO closed. Though it may seem like common knowledge to us, that is oils and things, to a tech, their job is to follow what the computer says, thinking on their own usually gets them in trouble more often than not. If you want to request a special oil, you'll definitely want to do that beforehand. Keep in mind, they'll have to slightly alter the process for doing that job just for that request as they're going around the built in GM system for service. Just food for thought. Nobody did anything wrong here and if it happens again in the future to any posters here, just know that they're simply not told any better. If you want to complain about something, take it to GM.