Just wondering if the Hyundai Santa Fe 2.7L DOHC is the same Chrysler sludger 2.7L DOHC. I know for a fact that the drivetrain (transmission & all-wheel drive) are Mitsubishi components. The reason I ask this is because my parents twin '02' Santa Fe motors seem to build up some sludge on the oil cap and dipstick even with premium synthetics like PP and GC (Filters used are P1 & Carquest Blue). Currently running Edge in the AWD Fe and the last of GC in the FWD Fe. The FWD Fe has about 3500 miles on oil and it is really dark with lots of engine noise, this truck however does sit for weeks without being used. The AWD Fe sees 6 days a week of straight highway trips of 60 miles roundtrip. Thinking of just doing 3k Chevron oil changes in the FWD & 10k with Pennzoil Platinum / Pennzoil Ultra in the AWD Fe. My parents need to run these trucks to 210k trouble-free miles. The AWD just hit 105k, gonna do timing belt in a month, and the FWD has about 70k on it. Thoughts and opinions please.