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old car leakes oil out after oci'??

1K views 7 replies 4 participants last post by  samonthego 
#1 ·
question for you older guys friend of ours just picked up a 72 cutlas all original everything all was good until he changed to synthetic 5w30 rather 10w30 it calls for he's stumped! cus oil's running out from everywhere why would it leak just like that fast?
 
#2 ·
all original everything
Maybe after 50 years all the seals got a little hard. I doubt the oil has anything to do with it. It would good to know more about the history of it and how often it was driven or how long it's been idle.

If it's been laid up for ages there's a fair chance that may be what's happening not that know the construct of the car.
 
#3 ·
If i recall many old car engine used the old Cork gaskets up to a certain Year. before they changed over to Rubber Gaskets. the old Cork gaskets found on older cars worked fine on Mineral oil. Problem lies when switching over to Synthetic Oil, because it soakes into the cork material and will sweat it out & eventually push it out through the Cork gaskets material causing a leak.

also many older engines rear main seal was made of (rope im not kiding) again useing synthetic oil would force its way out there. so... check the gaskets for Cork if its still got it he needs to swap them all out along with the rear main seal with rubber seal/Gaskets.
 
#7 ·
all depends on what the owner has in mind for it. if hes just keeping it stored away as a classic wich is the smarter rout to go. no need for mods if its a daily driver being driven yes a crate engine & new transmission would be a wise decision & you would make more power to move that heavy car down the road. not that the old engine cant handle it its just not reliable 50 year old car things get old & wear & get hair line internal cracks in the engine rods bearings etc, under pressure things snap

& break. that's the reason. and its not any cheaper rebuilding either if you can find someone willing to do it just a dyi' for your information some mechanics have made the mistake in the past to use the original "cast iron piston rings" the old vehicle came with in the old engines then run synthetic oil bad mistake to do lol because the original cast iron piston rings are made to run only on mineral oil for proper break in & seating purposes useing synthetic oil there after on those new cast iron piston rings will never seat properly.
 
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