Hi All,
I read with interest the thread on the advantages of using synthetic vs. dino.
Are there concerns with switching to synthetic on a vehicle that has been "lubed' with Castrol dino, specifically my wife`s 03 XC70 which now has 85K on it. This a commuter car, 100 miles a day of mostly hiway miles. Any potential RMS issues with a switch?
Thanks,
Rich

Hmm, you probably won't have issues - your car is *only* five years old.

The other school of thought is to use a semi-syn if you're concerned about old seals leaking (seriously, five years is NOT old).

I think you'll find the five cylinder engine to really like syn or a semi-syn. It will rev smoother, the turbo will be heaps happier, your gas mileage will improve, and best of all, your engine will be a lot cleaner than on dino. I have an 850 T-5 and I am using a Valvoline semi-syn so that's been my experience. My experience with dino oil in a normally aspirated 5 cylinder is the same - not so good. The engine runs a lot less lethargically and is cleaner with a semi-syn or syn. The cleanliness helps the flame trap to clog up less frequently, which is a good thing, since the last time it did, I blew out the rear engine seal and the engine caught fire when the oil hit the exhaust ;-).

Good luck.
Lucast