So 10-15 idling is not good, or okay on an engine that might have around 147,000 miles on it (don't know if it's been rebuilt or not)? Not to hijack, but I feel it's related.

 

Are you looking at the stock gauge? If so... who knows what your actual psi is.

Test it with an aftermarket gauge if you're concerned.

 

Ya never trust the stock gauge. Although, mine IS correct suprisingly and I only have about 10psi +/- 5psi at times at idle, about 30-50 driving, it varys. Tested with mechanical gauge. Im not to worried about it, I havn't had issues with it yet. I have just been using higher weight oil. 20-50 year round.