Oil Weights

[dawgn86]

I know there are a lot of opinions on oil weights / and synthetic vs dino.

Here is my case: I bought my PF new in 06. It has the auto transmission / 4.0 V6. I have changed the oil every 4000-6000 miles including filter. Always looked underneath the car for leaks, etc. I have always used regular oil / 10w-30

At the oil change at 107,000, I decided to switch to Mobile 1 5w-30 full synthetic. I now have 110,000 miles on it. Sinc the switch, I have had to replace my oil cooler gasket and now it looks like I have a small leak around my valve cover gaskets on both side. Very small, but a leak is a leak. Seems odd that this has happened since going to a lower weight oil.

Should I switch back to regular 10w-30 ?

Thanks

[smj999smj]

The only difference between 10W-30 and 5W-30 is the cold temperature viscosity. Nissan recommends 5W-30, which is what I've always used in my 06. Some might say the switch to synthetic from conventional oil could be the culprit. If you listen to the oil manufacturers, it shouldn't make a difference. The other thing to look at is that Nissan has had issues with engine oil cooler gaskets leaking for about a decade and your engine does have over 100,000 miles on it. Valve cover gaskets don't last forever, either, so there really is no way of telling for sure whether it was the change in oil or just normal "wear and tear," as they say.