Not to split hairs....but ....the "tolerances" do not change..rather...the "clearances" do change over time.

 

I will just stick with the Factory fill brand Mobil 1 and go up in oil viscosity to 10W/30 or 10W/40. Maybe this will help the minor oil seepage I am getting from the 5W/30 oil.

 

Any oil viscosity recommendations?

 

Nope, I'm one of those saps that just follows the manufacturer's recommendations for a street driven car.

 

Me too but now my car is no longer new. It's 100,000+ miles.

 

That's nothing for a well maintained LS engine. Have you noticed a power loss? Excessive oil consumption? Loss of compression? Low oil pressure?

 

None of the above. Just some oil seepage on lower part of engine.

 

Probably not.

 

Then use a 5w30 synthetic of your choice, and enjoy

 

5w/30 hIGH MILEAGE.

 

Then probably what?

 

I have no oil leaks running 5-30 dextose , or whatever they call it, with over 130000 miles on an 03 car.. maybe it was luck, maybe it was because nobody screwed around with opinions that figured they understood engineering well enough to run outside of the original engine specification. the car did spend some time as a corvette shop's auto cross car, so it was nice and clean but not a light duty queen.

speaking to marine experience, I used to be a working international sailor, with extensive sea time in all conditions. no only fair weather hobby stuff. whenever I was relaxing with the engineers, they had all the instruction manuals for the various systems they supervised lined up all around their rooms . They went strictly by the book . part of that was to have no surprises for their relief , and part was to avoid legal exposure if something drastic happened that involved a system under their responsibility . besides the potential for at least a four billion dollar plus mistake, if working a supertanker , every seafarer knows that if you get involved in court testimony, you have just blown all your vacation time. there might have been better maintenance approaches, but if you are talking to a lawyer, going by the book is the best answer.

I'm not trying to contest any opinion offered here. I just pass on what I have read , and once in a while relate personal experiences from the "I have an old car" learning curve, in the hope that maybe it might make somebody else's learning curve a little less steep than my own.

 

You are describing it as seepage; I, nor anyone else knows what your criteria for seepage is. Leave it alone or fix the leak, your choice. BTW, a 5W-30 and a 10W-30 motor oil will be within the same viscosity range at operating temperature.

 

Going to a thicker oil will have little effect on an oil seepage/leak issue, and isn't a good reason in and of itself to change oil viscosity. I also think the bearings and other internals are fine, unless there's a knock present, or see the oil pressure has dropped slightly. The first number (0w, 5w, 10w, etc.) is the approx viscosity when cold. The higher the number, the more resistance to cold flow you will have. One could actually increase wear by going to a thicker (when cold) oil. It may not be a world of difference, but 5w-30 and 0w-40 have similar cold flow values, with the 0w-40 having greater protection at high temps. It is what I run in my LS7 C5. Today, I guess it's a pick your poison thing. But it is hard to find a bad synthetic oil brand...

 

Go with the "High Mileage" 5W-30 synthetic oil for engines with over 75,000+ miles. We are at almost 102,000 miles.

 

At almost 102,000+ miles this LS-2 engine has lead a very good and easy life. We don't beat on it and most of it is highway miles. It has had frequent annual oil changes on the 5W/30 Mobil 1 factory fill for the past 20 years.