thoughts on stop leak
 

This is probably a ridiculous question as I believe most benz owners on this forum treat their car like their baby(some better than their baby)but I'll ask it anyway. I've got a nasty oil leak from my 87 560 sel and it appears as though the tranny might need to be moved to get to it. Seems like a big job for a non threatening problem. Just tired of messing up driveways. What are possible hazzards of a stop leak additive?

The only thing stop-leak does is swell up some seals.
You can try it but, if the leak is of a " serious " nature, it won't help much, if at all. ;)

i wouldnt be
 

afraid to try. not much hope of it working though unless leak is minor.

tom w

Hey Jeff. Just a thought. Ck and see if the valve cover is where the leak is coming from. If it is there, it is an easy fix. Or, take off the breather and start the car. Shine a flashlight in between the intake manifold and throttle body to get a look at the valley under the intake. If you see oil there, chances are the head gaskets are leaking. When this happens, that valley fills and drains in an over flow hole and runs out a weep hole from the back of the engine. It would make you believe that the rear main seal leaking. I had this happen to me diagnosing an oil leak. Funny thing, the engine ran ok despite the bad head gasket. Hope this helps.

if yer sure its the front pump seal then nothing will help
except the o ring replacement. by now it has cracks and
nothing works on that. most sealers work very short term and then
make the trans totaly useless. don't use it.

george

oil leak / sealing compounds
 

Just my two cents: I'm, in general, against the use of leak sealant additives. The molecular size of the sealant is much larger than that of oil and the various additive compounds in oil, so as the oil seeps around a seal the larger sealant molecules build up and do a fairly good job of stopping a leak, but only for a time; the oil detergents eventially flush out the sealant, at least that is my guess. But, my big bias and this is only my thinking, only someone who has checked these things know's the answer, is that an oil filter is treated just like a leak and so the surface area of the filter get's reduced; I also wonder if any machine fit in the engine suffer's the same fate. I've never met anyone who had good reason to believe a stop leak sealant starved their engine in various places of oil, but my guess is it does partially seal around machine fits. I tore down an engine for a guy in the 60's who had used stop leak for a long time. This was a motor that used detergent oil and he had been good about changing the oil. But, there was a layer under the typical oil gunk, right against the metal that was different from any oil gunk I'd seen before. My guess is that sealant was the layer. This is also very bad for heat transfer. Keep in mind that a piston oil scraper ring, at least in a blue-printed engine, leaves behind a single molecular layer. This single molecular layer of oil is what separates moving metal from moving metal, and is very adequate in doing so. Messing with dynamics such as that by adding stop leak I feel is very high risk. I certainly wouldn't do it period, and with the high-quality engine's MB manufacture's the don't do it also applie's. As those have suggested, first see if you can find the source and calculate the cost/benefit to fix. I don't mean this as a wisecrack, but putting some cat litter where the oil leaks on the driveway (after it's been cleaned) does the trick. Then just sweep it up every once in a while. Hey, maybe this can replace vegetable oil as an alternate fuel. (Now I am wise-cracking) But, squeezing the oil out of the cat litter might prove problematic. So, my bottom line thinking, as if I don't have enough line's in this post is that the best thing to do is fix the leak, the next best thing is to live with it. However, maybe in front of living with it, go with the highest viscosity oil your engine call's for in your climate. I had a nagging and worsening oil leak in my 94 Cadillac SLS, which required lifting the engine out of the bay to fix. The engine had a quarter million miles or so and still ran strong (my wife traded it for a Jeep), so I started running straight 40W which slowed the leak dramatically.

i think
 

ralph makes a lot of sense.

tom w

ok, this thread is getting wacked out.
i assumed the original post was about a trans leak. rereading it now
makes me realize that its not clear.
so what type of oil is leaking?
most stop leaks for trans and eng oil are of the chemical type so
pose no threat to plugging up filters. non that i know of anyway.
ones that have stuff in them are for coolant leaks and this don't got
no filters in anycase i know of.

george

i assumed it
 

is an engine leak. that he needed to pull the tranny to get at.

tom w

Great advice from everyone. The leak is engine oil and it is allover the undercarrige of the vehicle. This is an 87 with 117,000 miles on it. 40,000 of those have been put on in the last 20 months. California car that is like new but has to spend a couple months in a canadian winter. I'll have to do a clean up underneath and see if I can identify exactely where that leak is coming from. I am against using any temp fixes that could equate to bigger problems down the line. Also curious if anyone has any thoughts on mechanical upkeep issues on a car with this mileage?

el duderino

There are 2 kinds of engine stop leak. One is an oil viscosity improver (OVI) like STP. It basically is a very thick oil -- you can guess how it works.

The other is an additive that swells seals -- similar to tranny stop leak. This is the stuff you should try. It sound to me like your rear main seal may be expiring, which ain't a cheap fix. However, be sure to check around your valve cover gaskets!