1. If I have low oil pressure at idle (low as in "check gauges" light comes on) but get about 35-40 psi at around 2000 rpm, would adding a quart of lucas to my next oil change help increase oil pressure at idle? 2. If I add lucas once, do I need to keep adding it every oil change? Is it something like when you start using it, you can never go back? I purchased a 2000 Jeep Cherokee with the 4.0L in December. Only 109,000 miles. No ticking, clattering, or knocking. Past owner blew the head gasket and coolant leaked into the oil, wearing away some of the bearings. I asked a mechanic if I should up from 10w-30 to 10w-40, and he said 10w-30 with a quart of lucas would be a better option. I already changed the oil pressure sending unit, I have seafoam in the crankcase to help get sludge out of the oil pump, and the mechanical pressure test confirmed the gauge is reading correctly. If the lucas doesn't work, I plan on installing a Melling High Volume oil pump, which I'm told worked wonders in similar situations (yes, i know volume does not equal pressure, and it may lead to other problems down the road, but 90% of the people who install them say they solve the oil pressure problem. Basically my back is to the wall right now- I can't even sit at a red light for 3 seconds without having to rev the engine to 1000 rpm's or so, and it only gets worse with the upcoming summer heat (I'll be in Montgomery this summer)). If anyone has any experience with these oil pumps, that advice would be greatly appreciated too.