cause i have 3 of 4 older cars that never leaked a drop....#4 (northstar) had an occasional drop periodically. been using high mileage full synthetics for the least 2 years. 6 month intervals, mobil 1 ep hm (x2), castol edge hm, and pennzoil plat hm in that order. they're all springing leaks at once especially now with the pp. 2 different mechanics tell me that high mileage full synthetics are cleaning too well and removing stuff that was keeping leaks from happening or at least showing up. The cars have never run this good....smooth quiet engines. But I've had the following: rear main seal+oil pan gasket f250 5.8....oil pan and timing cover gasket buick 3.1....oil cooler line, crankshaft, crank position sensor, timing cover with a rear main beging to show up on the jimmy 4.3....and the newest is valve cover, oil preasure sensor, sending unit, pan gasket, half case, and rear main on the cadillac.
They told me to either use conventional or ideally a blend and one said to only use a high end full synthetic every 30k max to clean anything up for a 2-3 k interval.
All i know is I've dropped a conservative $5 k in the last year strictly on replacing gakets. checked all the pcvs and they're all clear so it isnt a pressure issue.
Been using these 2 different shops for years and am fishing buddies with both mechanics. The bigger shop owner tells me that hes seen me buy 4 cars in last 6 years that didn't leak and now they're all springing leaks in the last year or so. The other guy whom I've been friends with for 15 years works on on a few fleets of vehicles and he says that the local pharmacy has a fleet of American made vehicles older than mine, that don't leak as often as mine do. They both agreed that the engines run like champs and when they've pulled stuff apart, they'll call me down to look inside (cause i like to see that stuff) and they always remark on the cleanliness of my older vehicles internals for their age.
i know it's not the popular opinion that "syntbetic" oils cause leaks but well.....1 leaker i can agre with that statement.....2 leakers is a coincidence.....3 leakers is suspicious.....4 vehicles all leaking at the same time when they didnt previously? hard to believe especially since my boat engine (merc 3.0) gets mostly blends and doesn't leak at all.
idk both the guys who fix my cars tell me to switch to a conventional and change it every 3-4k or a blend (both leaned toward blends) and do every 5-6 k. i do my own oil changes so they aren't trying to profit off of more frequent changes.
any who thats the long version and the reason behind this question.
