Additives to fix rear main seal leak?
 

Has anyone used additives to attempt to stop a leak in the rear main seal?

I found positive endorsements online for AT205 and "No Leak", and some mixed reviews on others ... but could not find any threads on this forum on the topic. Before I spend $800+ to replace the seal I would like to try one of these additives first.

Thanks. John

What year/model accord do you have? Automatic or manual transmission?

I have no specific brand that I can recommend.

Just make sure the additive will not block oil flow through the engine. Also, not sure how much oil you are leaking, but always check the oil level. Keep a quart or two in the trunk, incase you need to add some when driving.

I think that these additives will work when a seal is slightly worn, because the additive makes the rubber seal swell.

An additive will not work on a torn seal, popped out seal, or a very worn seal.

Sorry, I thought I had my car listed in my profile somewhere that would be shown ...

1996 4dr EX F22B1 automatic, 230k miles

I bought the car used about six months ago. When I first got it we were seeing 1-2 drops every time we parked. I replaced the distributor o-ring and vtec solenoid gaskets a month or so ago, both of which were leaking, and the dripping seemed to almost stop for a few weeks. But recently it appears to have increased to several drops (1.5" stain on the asphalt) now whenever the car is parked. I'm pretty sure it's coming from the rear seal as I've checked the oil pressure switch and under the oil filter and they are both dry. Oil pan also seems pretty dry on the front side of the engine (front seals were replaced by previous owner).

However I also switched to Gastrol GTX high mileage 5w-30 to replace the Jiffy Lube standard oil, in hopes of stopping this leaking entirely, but I wonder if this has actually made it worse by cleaning out deposits and allowing bettr oil flow around the seal?

In any case it's not a large drip, but it's enough that it leaves a noticable spot on the ground, and it looks like it's on the increase, so I would like to take care of it one way or another.

Unless I hear otherwise I will probably try to find the AT205 first since I have seen no negative comments online about this particular brand.

Thanks. John

Any additives you add to the engine what ever it may be stop leak for radiator,or main seal leak repair there all just a quick fix to the problem and from experience i have seen these additives do more damage when the owner decides to fix it proper,i dont recommend using any stop leak cause when you do decide to fix it proper it just makes the job more time consuming for the mechanic who is going to fix it.
But if you do use the additive do your mechanic a favor and change the oil and filter after driving your car 50 miles so the additive just seals the seal and nothing else.

So it's been over a year since I last posted to this thread ...

My strategy for the past year was to use Gastrol GTX High Mileage oil 5w30, and 1-2 weeks prior to the oil change I could drop in a bottle of Barr's Rear Main seal leak stop. I also replaced the PCV valve with an expensive one from Honda, just to make sure that wasn't causing a problem.

That seemed to work for several months as the dripping eventually stopped, but in recent weeks the drip is starting to come back again.

I haven't done a compression test yet so I don't know if worn rings are adding too much pressure in the crankcase. But one thing I can do is to start ratcheting up the viscosity of the oil. I live in Northern California, and according to the CD5 recommended viscosity chart pretty much any common oil weight should be just fine here.

Question, should I up to 5w40 or 10w40? I would like to do this as gradually as possible so I don't "overthicken" the oil. Currently my feeling is that the dripping occurs when the engine is hot, so 5w40 would be the more appropriate first step.

Any thoughts?

As far as oil grades go, 5W-40, 10W-40, 15W-40, or even 0W-40 all have the same effective weight/viscosity when at operating temperature, so it would matter not which one you use from a blow-by perspective. That said, I seriously doubt you'll notice any difference in leakage compared to your current oil, in fact, even if you went as light as say a 0W-20 you would most likely still not notice a difference.

At this point I would stop messing with it and just keep adding whatever oil you can find by on sale by the case; adding oil costs a heck of a lot less (from both a time and money perspective) than replacing the rear main seal.

At that many mile crank endplay should be checked before investing into a rear main seal. I haven't seen any additives make a difference other stopleak.

R&R'ing the trans and replacing the seal isn't a bad job, even on the ground with a floor jack and jack stands. Four hours if you're fast, a whole Saturday if you take your time. The hardest part is probably getting the axle nuts off.

The best thing to do as a stop gap before replacing the seal is to get some brand name "high mileage" oil. These have their own additives that help to swell the seal to help stop the leak. It wont stop it altogether, more than likely, but it will slow it. I've used these a lot previously and they work well. My fave was Castrol High Mileage. It's the green container one. Also, use 10/30 oil instead of 5/30

Yes that was my first change, to Castrol GTX High Mileage. However I have been using the specified weight for the car - 5w30 - which is on the thinner side, so I would like to thicken it up a bit. Therefore the question of which step to go .. 5w40 or 10w40?