So I still havent found my oil leak, but what i'd like to know is if it was possible that the leak was caused from going to synthetic oil from regular mineral oil?

If so, is it also possible that the leak will stop if I refill with regular mineral oil?

Or am I buggered?

It's been off the road for 6 weeks now, If I can't get it fixed, I'm getting rid of it - maybe buy a C5 instead.

 

Why would you use syn.... ... .stick with something like Valoline Max Life for engines with higher milage.....this oil has additives to make the seals more plyable.....your engine was not made for syn. oil.....unless it is a new engine....what is your milage????? Your Bio shows you own an '86....so why did you use the syn. oil????

tony :hurray:


[Modified by oldace84, 2:53 AM 2/7/2003]

 

Most likely. The synthetic ate away sludge that was making up for bad seals somewhere. Is the oil leaking/dripping on your driveway or exhaust? if not, then it's blow-by (yer screwed) or valve seals (easier). I think part of the reasons the seals degrade in the first place, is because of excess contaminants in the oil building up on seals and preventing proper lubrication and swelling of the seals. The acids probably eat the seals over time too, and the contaminants help to wear the cylinder walls.

Since I've switched to Mobil 1, I've had a few leaks, nothing major. I'm getting some smoke on start up (oil getting past valve seals when car sits overnight), and I had some leaks from the valve covers and even the drain plug. I would say, if your front&rear main seals aren't leaking, then don't switch back. The other leaks aren't as hard to fix. The added protection of synthetic is worth the hassle IMHO.

As far as an engine being 'built' for synthetic or dino... Our V8's internals were designed in the 50s and 60s, long before synthetic oil was considered or even existed. Synthetics were marketed as a replacement for dino oils before they were ever poured in the assembly line. (I think Mobil syn can out in seventies, but wasn't in factory Corvettes until the LT1.) As far as breaking in an engine, oldace is right, but after that it doesn't apply.

Synthetic oils were built for our engines, not the other way around.

 

If you don't have oil leaking on the driveway, check the valve oil seals. Maybe it is just me, but if I have an oil that is working ok for me , I don't switch ( as the old folks say, don't switch horses in the middle of the steam). I have heard of some reports years ago of problems with switching from dino to syn but not recently.

 

If its on the ground its probably the rear of the intake manifold, thats pretty common. The 1 piece rear seal is possible, but not as likely.

All you have to do is take it off and replace the gaskets.

Its likely that the Mobil detergent package ate away the sludge keeping the oil in, so it did its job in cleaning up the motor internals, its also an oil that will find a hole if it can. You should stick with Mobil 1 and just replace that gasket.

 

It's dripping on the exhaust (driver's side), near the oil filter.

I don't have the time/skill/equipment to take the engine apart to find out which seal/gasket is leaking, but I don't want to get ripped off at the shop either.

I was hoping I'd be able to put some more oil in and the leak would go away :D

It's lost quite a bit so far, doesn't even register on the dipstick right now.

 

This may just be a urban legend but I have always heard that if you switch from normal oil to synthetic oil it will leak. Especially worse on higher mileage engines.

My old Firebird I had only had 40K on it when I bought it. Did not leak any fluids. When I did my first oil change I went with Castrol synthetic blend instead of the Valvoline the previous owner was using and it started leaking. FWIW.

 

Maybe the oil filter is either loose or too tight. Overtightening the oil filter will cause a leak.

Also, sounds like it might be the oil cooler seal. That's a pretty easy fix.

 

It seemed okay until I topped up with the Mobil1 synthetic, I think I used an ultra thin version too (5W-40), so that probably didn't help. The motor has about 80K miles on it, and it's an '86 so it's a little old. I haven't touched the filter since the last service, but it's possible that it could have worked loose.

I'm going to try filling with regular oil and see what happens first - then if it still leaks and I can find a jack that will lift it high enough, I'll check the filter and seals.

:cheers: for the advice guys.

 

It doesnt work that way. :nonod:

 

I made the switch to 5W30 Mobil1 on my '88 when I bought it last June. 62k on the odometer and it doesn't leak or burn a drop!(I must be lucky or something)

Anyway, a synthetic will always be better than a dino oil. Synthetics have been around since the begining of WWII, I have heard that the oil used in Mustang's was a synthesized oil.

You might try leaving the Mobil1 in, as over time it will tend to make seals swell. I think the oil cleaned up deposits that were blocking an old leak, and the synth is now leaking out. Give it a chance to swell the seal, and try to clean up the area around the leak and determine exactly what is leaking. We can help you from there.

Good luck with your decision. For more information, do a search on this forum http://theoildrop.server101.com/ubb/ultimatebb.php

J