99 Infiniti i30, oil in spark plug hole?

I had the exact same heart attack moment when I bought the infiniti and was reading the owner's manual. What, 5w30, I thoughted my nissan wanted 10w30. took out the Nissan manual and was like, What? 5w30? why the hell have I been using 10w30 all these time?

I might have mis interpreted the information in the manual back then. it says if temp is above 32, 10w30 can also be used. I read it as

10w30 is preferred for temperature above 32. I am in the san francisco bay area so most of the time it's ok.

Is 5w30 a thinner type than 10w30? If the temperature is warm, will I get better protection for the engine for using 10w30?

Raymond

Will driving on the highway for a long time (say 4 or more hours) put more stress on the car than a shorter trip (say 30 min to 1 hour)?

While highway driving is better for the car than city driving, I think trips longer than 1 or 2 hours puts a different kind of stress on the car. I sometimes feel my car drives slightly better after a few days of normal commute (15 minutes on the highway) after a long trip, just like me when I need to recover for a day or two after a long trip. ;) I can't think of a good reason why it would, being that everything is metal and mechanical, but I thougt it did.

Raymond

Yes and no.

The 30 is the important number, that's the viscosity when hot. Truth is, "better" protection comes from a lot of factors, and a viscosity of "30" covers a lot of ground. So one would assume that a 5W30 might be slightly thinner than a 10W30 when hot, but it might not be. e.g. a synthetic 5W30 might be formulated to be thicker when hot than a conventional 10W30 because the synthetic is more temperature stable and requires fewer VI additives... it's a complicated subject and there are no easy answers.

Best thing to do is simply use a quality motor oil that meets the mfgrs. specs... if you want to second guess the mfgr, you have a big learning curve ahead of you and you will find then that not all oil mfgrs. publish all the specs that you need to make decisions.

Note that that advice is only good for modern engines that don't require lots of anti-wear additives (don't have flat tappet cams) if you have an older car with flat tappets, all the above does not apply - you *do* need to do some research to find an oil that won't wipe your cam.

nate

Not unless the car is a hopeless POS with an inadequate cooling system or something. The longer the trip, the better.

Besides, 4 hours hardly qualifies as a "long trip." Hell, I used to jump in my '73 Satellite and drive 12-14 hours at a time except for gas, food, and restroom breaks.