Saab Link Forums banner


49161 Views 11 Replies 9 Participants Last post by  Jack Straw
I am going to do an oil change on cujo (1993 900c) and was looking for input on what synthetic oil / regular oil is best for my car. I work at vip and have access to mobil 1, penzoil, Castrol,havoline brands. and what is best transmission oil do i use???

I would like synthetic but not sure if its best for the vehicle. It now has 310,250 miles on it. Thanks!
1 - 12 of 12 Posts
I run Royal Purple 10w-30 for the engine and Redline MT-90 in the trans.
there are not many places to be buying oil and where i am having my workplace do the job I have the oil available to me that the shop sells we can however get the redline its a special order kinda thing.
Just make sure the grade and weight are correct for your car. I'm referring to the API/SAE grades for service ( the XX/XX) rating. With your mileage, unless you are doing a complete overhaul, I'd probably stick to rock oil (pertroleum). All the brands you listed are dependable oils, though each can have it's quirks in specific engines.
c900s are NOT particular about oil like the newer sludgy engines are.

Is you car a turbo? If not, just put 10w30 or 10w40 mineral oil in it, honestly just use whatever's on sale. If it is a turbo, you may choose to use synthetic, again, whatever's on sale.
I am going to do an oil change on cujo (1993 900c) and was looking for input on what synthetic oil / regular oil is best for my car. I work at vip and have access to mobil 1, penzoil, Castrol,havoline brands.
Any of those would be fine. Running synthetic is not needed, and IMO is just a waste of money. As for the trans oil, you should run an MTL that is designed for a FWD car. Not gear oil, not motor oil. Something like GM-syncromesch or the royal purple that's designed for cars with manual transmissions that calls for ATF or motor oil.
I did some cocktail napkin math about my driving, with very conservative estimates. I've been driving approximately 17 years, and with a low average number of miles driven per year at 25,000 miles, I'll say that I've driven approximately 375,000 miles with two internal engine mechanical failures. However, neither failure was due to the oil itself. My first internal engine failure was spun connecting rod bearing on my 1960 Volkswagen due to an oil leak that developed at the oil pressure sensor--my second mechanical failure was with a 1965 Volkswagen which dropped its number 3 exhaust valve (a common failure with the old air-cooled cars for those who don't know).

The only oil I ever use is Castrol's always done the job and never let me down. Besides, unlike some of the other brands, if you're particular enough to want to use the same brand all the time with every oil change, it's available just about anywhere.
See less See more
in past years, i have heard of independent tests showing that the Castrol GTX oils doing rather poorly on the 'shear viscosity ratings'. a bit more info available here.

i have always used Valvoline semi synthetic... i like the blue container :wink

dont switch to synthetic at this point, or you are almost sure to develop leaks.

ahh, the endless oil debate... no matter what forum you are on, this will come up again every couple months. props to regular TSL'ers for not giving hell and actually answering questions... more info can be found using 'search' to see what has been said in the countless other 'oil' threads
I did the change and chose mobil one synthetic and redline for the trans and like the fact the car runs quieter and smoother...happy camper so far...
When I last changed the oil in my 81 turbo I went with Penrite (Australian-made) 'Sin-10' engine oil.

Up to that point I'd been using Shell Helix-Ultra but that seems a bit light at its 5w30 rating and since the stock specification is for a 10w rated oil, I probably won't use Helix Ultra again.

I believe SAAB actually specified either 5w30 or 5w40 (can't remember) synthetic for use in all 900 turbos in a service bulletin at some point.

The 5wXX just means that the oil is already closer to it's specified viscosity (the xx) at cold start than 10wXX. It's good stuff to use, if you can find it cheap, especially in winter.
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.