I have a 740 volvo turbo wagon with 209,000 miles driven and have been using castol semisynthetic oil for years. Does it make any sense to switch to full synthetic oil at this point? I would think the changeover would be favorable for an older engine such as mine.

Hey Rich,


As long as the motor is in good shape and has been cared for, (which I'm sure your is/has been), I think you'll be fine running a full synthetic. Like Ryan said, its a good idea with the turbo engines. If you have any concern about sludge or seals, run a Auto-Rx clean/rinse phase before switching. Its good stuff. Many like the Mobil 1, which is a good oil, I use the Mobil 1 "Turbo Diesel Truck" oil in my B234. Its one of a few oils available in 5W-40, and while marketed for diesel engines, it also has the API 'SL' rating for gas engines. Its very robust, as its related to Delvac 1, which is Mobil 1 for Diesels. I think it would be great for a turbo motor. It runs well in my 16 valve motor. The other types are Mobil 1 are very good as well. Some really like the 'German Castrol', which is a 0W-30. Its quite thick for a 30 weight oil. This is not the same as the other weights of Castrol Syntec that are made domestically. Often referred to as GC, its made in Germany and says so on the bottle. The only place that I know of that carries it is AutoZone. There are other good oils out there as well. The 'Bob Is The Oil Guy' forums are a great place to learn about oil and lubricants.



Regards, Jon 'Uncle Olaf'

Yeah. I'm moving to synthetic soon - I went to semisynthetic to get out all the supposed sludge hiding somewhere because I used pennzoil.
The major concern people have is that going from regular to synthetic is blah blah plugging up your oil filter with crud so you have no oil flow, and that seals will swell, then shrink because of the different type of oil.
I will point out that most of my oil consumption (all of it if I don't ride my turbo hard) disappeared when I went to semi-syn.

-Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

Sounds good. The smart people always suggest using synth in anything with a turbo. Mobil-1 is universally the brand of choice.

-Ryan
--

Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars