GM: Mobil 1 vs Castrol [Archive] - Forum


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Mike Jung
05-05-2008, 06:20 PM
Anyone work for GM, a GM dealer, Mobil 1 or Castrol ?

Know what's up with GM's selection of synthetic motor oil ?

I went to get an oil change at my local Pontiac dealer, for my Mom's Sunfire GT.

They are now promoting (& so is GM Canada):
Castrol SLX Professional 4718 5W-30 synthetic motor oil.
That is made by Castrol US for GM Canada.

What happened to Mobil 1 being GM's preferred synthetic oil suppler ?
(They still had some Mobil 1 5W-30 oil beside it for cheaper, by $0.50 per 1L bottle.)

PS: My Mom's Sunfire GT also gets Castrol Syntec 0W-30 too ;) lol

05-05-2008, 09:44 PM
At my old dealer in Corpus we had Mobil 1 on hand for all synthetic oil changes. At my current dealer in Austin we get Mobil 1 in bulk. Never seen M1 in 55 gallon drums before. Since M1 is the factory fill for most Caddies nowadays, that's what we still use. I think it might just be a canadian supplier thing.

Also, another Castrol 0w30 user here. Runs great in the Cobalt but I should really do a UOA. I've had a mild lifter tick on cold start ever since my thermostat was stuck open for a few weeks in the middle of winter.

05-05-2008, 09:48 PM
I though it was M1 for GM, its what Chrysler uses.