[Dr. Jerryrigger]

I tried some 0w30 last winter. It was surprising how noticeable the difference was, though I can't say anything definitively about mileage, I would guess it had a very small improvement. The most noticeable thing was when starting the car cold the RPM's jumped up 600 from where they normally do. When not in gear it would change RPM's quicker i.e. if I quickly opened the throttle it would jump up near the red line and drop back down in noticeably less time than it would with conventional 5w30. I find the same to be true, but less dramatically between syn and conventional of the same weight.

If I was racing my car I would use 0w30. But I'm doing far from that, and engine life is of greater importance to me than mileage. I'm not really sure what to think about this topic, but I won't be going back to 0w.

The last time I changed my oil I use full syn 5w30, that was about 7.5k ago (recommended change at 5k), but it leaks, so I've added a qt of syn, and 2 qt of conventional since then. I'm sure someone will tell me that it's bad to mix (and it might be), but I was out of town, only had 5 bucks, was down more than a qt, and syn was $7.

I'm thinking for my next change I may try 10w30, my engine is old, and there must be some play in components that would benefit from thicker lube.

5w30 or 10w30 is recommended, but 10w is not recommended for temps below 20F (or something like that). But they came up with that for an engine with 0 miles, mine has 140K.