So I'm frustrated with a small oil leak on my engine. (A few drops in the driveway with no real noticeable drop in the oil level.) I haven't yet tracked down the source and I'm hoping that it is not the rear crank seal. BTW, I've recently replaced the valve cover gaskets and I have not yet eliminated the oil pan gasket is the source of the leak.

If it turns out to be the rear crank seal that is leaking, as an alternative to pulling the engine or transmission I found that there are oil additive products that claim to fix these types of leaks by swelling the seals.

What is the collective forum wisdom on the use of these products such as Bar's Leak Rear Main Seal Repair (https://barsleaks.com/product/concen...n-seal-repair/)? Do they work on small leaks? If so, how long? Can they harm anything in my engine?

Related to this, how much should I worry about a rear main seal leak?

Thanks,

Christine

 

I would not recommend any of those quick fix type deals. they can cause problems in the long run for other parts of the engine.
I would also check the oil cooler lines right next to the oil filter because those are known to leak.

If it is the rear main leaking and its only a couple of drops, I would personally just drive it until you need to pull the engine or transmission out of it. Rear mains are a ton of work to change.
With an automatic transmission, the leak will just make a mess but should not hurt anything. Just keep checking the oil.

 

Thanks. I've never liked the idea of the stop-leak products for coolant leaks as they introduced materials that adhere to surfaces and can clog passage ways. It was only recently I even heard that there were products for oil leaks which worked instead by swelling the seals themselves (supposedly).

I have replaced the oil cooler lines and the gasket and o-ring for the oil cooler line adapter so I'm comfortable excluding those from the origin of leaks.

I suspect the oil is leaking from the oil pan gaskets. It is only a few drops and I do have an automatic transmission so I just might have to live with it.

 

I agree with ChuckNTruck.
Never liked these products and usually they may be a quick fix but as quickly the problem comes back sometimes even worse.

Nevertheless I would investigate the leak to make sure you know where it is coming from.

Blazers are quite dry engines and may leak from different places just a little bit. Know places and remedies and AFAIK none of the minor ones are deadly to the engine. Wary thoug with leaking from plugs in the block!

- Oil pressure sensor (older ones on the back of the block next to distributor. (New sensor or gasket/O-ring)
- Head gaskets at the rear corners. Should really only be a bit of "sweating", no drops or running down the side of the block. (Well that's a tricky one which mostly ends with a rebuild. The least is new head-gaskets but then you open the box of the pandora... )
- Oil pan gasket in various places. (Sometimes just tightening the bolts to spec can stop that leaking. To specs means very little torque not to break the bolts or deform the pan rim.)

I'd give it a good washdown paying attention when pressure washing to have a hot water pressure washer and not to spray between gasket separated parts and electrical or electronical parts. Is a bit of a hassle but a quick way to get rid of the gunk from the outside of the block, transmission, oil pan and suspension parts. Let it dry or dry with compressed air and then underneath with some brake cleaner. Especially where you suspect the leak you want a dry surface such as the oil pan (easy) or the rear of the block (o.k. with some fumbling).