I know that this subject has been thrashed out time and time again but I am getting ready for my next oil change on my 97 GDI Pajero and am a little confused. In my past life as a motorbike rider I swore by synthetics. Since my older days I have gone semi-synthetic using Castrol Magnatec. Just recently, I have "heard" throughseveral sources that these oils work well when clean and on cold start-ups but tend to collect debris as the oil gets dirty which of course makes the lubrication between parts much like a cheese grater. Not having re-built an engine in some 20years can anyone offer thier thoughts on what is the best overall oil to use?

Jim
NZ

Benckj, there are two I like; neither is synthetic and both are in the lower price range. Both hold their viscosity better than any others I've used in their price range; and both feel more slippery than others when it's time to drain them. Valvoline (not the racing formula, though I don't doubt it's better) and Castrol. I can't tell you chemistry of either, or how their dielectric fields cause contaminants that are too small to filter out to just precipitate out of solution or what bases are included to neutralize the acids in the blow-by gases from the combustion chamber, etc... I do know that both of these hold my oil pressure in a smaller range from low to high temperatures than do any others I've used.

I swear by synthetics in an engine that I want to get maximum life out of, or plan on thrashing the ba-jesus out of.

There isn't really alot of difference anymore, due to the bends, and the additives, but in a high horsepower motor, or an engine that you want to run a long time you are looking for certain things.

fully synthetic motor oils will resist break down better than "dyno-blends." They also handle radical heat swings better.

In a turbo charged engine this means less build-up in the lines and turbo bearings were temperatures sky-rocket. I believe there is a technical term... coking maybe?

I also run sythetic in any motor that I want to last for a long time, also because it resists breakdown better than dyno belnds, but you also mentioned this...

- I have "heard" throughseveral sources that these oils work well when clean and on cold start-ups but tend to collect debris as the oil gets dirty which of course makes the lubrication between parts much like a cheese grater. -

There is a reason that it's getting dirty faster. It's picking up more intrusive particles. you should never run dirty oil, synthetic or dyno.

If you are running a blend of oil and it comes out clean after 3,000 miles, you should look into what it's doing in there, cause it ain't cleaning anything.

I see alot of guys switch to synthetic, and go back to dyno right away because "the oil was alot dirtier."

Well, of course it is, it was doing a better job cleaning. By running dyno again your gonna leave all that dirt in the engine that the synthetic was cleaning out.

So in the end, the advice that I would give anybody is the same advice that I heard a long time ago from an old, old race engine builder.

"Sure synthetic is good. But the best thing for an engine is keeping good clean oil in it."

In a motorcycle you change the oil more often and use a different oil than you would use in your car because the oil in the motorcycle lubricates the gear box and the engine, thus the oil gets dirty quicker. If you read in the owner's manual of a motorcycle it says to use an oil that meets or exceeds a specific rating (SP, SY, etc etc etc) that I don't remember off the top of my head.

If you're not running a turbo, I wouldn't use full synthetic.

I use Castrol with startup protection (the same as adding STP oil treatment).

I change my oil every 7,500 miles (which is what the owner's manual says for regular driving). If I were driving off road, racing, lots of city driving, or just driving my car really hard, I'd change it more often (say every 3,750 miles which is what the manual says for severe driving). I'm sure I'll get some crap from people about that. But, if I changed my oil every 3,000 miles, I'd have to change it every month and a half, which doesn't make any sense.

Thanks for all your thoughts. I have read a bit more on oil and additives so I can make an informed decsion. Its a worry when you do your research then someone comes back with a throw away comment about what you are using and you wonder if you got your facts messed up. Don't want to really find out I made a mistake after the motor blows.

Jim