[68WarDog]

What is the safest heaviest oil viscosity I can run in my 455? I have a rear main seal leak, and the plan is to remove the engine this winter for repair. But right now I want to drive the car without oiling down the driveway. My rod clearance is to RA 4 spec, 0020, mains 0025..Thanks

[grandam1979]

20w50 or just 50 will work just not great once it gets cold. With that said it’s not going to slow the leak much if at all.

[68WarDog]

Originally Posted by grandam1979

20w50 or just 50 will work just not great once it gets cold. With that said it’s not going to slow the leak much if at all.

Thanks, right now I'm running Amsoil 20w50 full synthetic. I'm hoping changing over to a conventional blend like Valvoline VR1 or straight 50 will slow down the bleed. I had shoulder surgery and the shop assembled the bottom, leaving the antirotation holes unplugged.

[Kenth]

Summer straight 30, winter or all year 10W40 for RAIV specs.
Straight 50 or 20W50 is aimed for engines running at 130° C.

FWIW

[David Jones]

You have a correctly plumbed PCV?

[68WarDog]

Originally Posted by David Jones

You have a correctly plumbed PCV?

Yeah manifold, carb and open breather.

[68WarDog]

Originally Posted by Kenth

Summer straight 30, winter or all year 10W40 for RAIV specs.
Straight 50 or 20W50 is aimed for engines running at 130° C.

FWIW

Since engine only has about 2k , been running conventional Castro 10w40 and had quarter size spot on garage floor
Switched over to 20w50 Amsoil and leaking bad. Plan is to pull engine on 2 months to fix. Trying to enjoy the car while weather is nice. If I go 50w for now, garage never get below 50 degrees.

[RocktimusPryme]

FWIW, just something to try. Mine was somewhat similar. When I brought it home it barely dripped, but seemed to be marking it territory more and more. I had also assumed rear main seal.

A few months ago I got under the car and retorqued my oil pan bolts. Now it’s back to nearly dry again. Don’t go nuts, but see if they are loose. Might save you pulling the motor.

I’ve used both standard and synthetic. I really doubt you will solve much with an oil change.

[chiphead]

You can try a conventional high milage oil. The seal swellers will slow down the leak for a while by making the seals softer and swell slightly. Try it if re torquing the gaskets don't help.

[68WarDog]

Originally Posted by chiphead

You can try a conventional high milage oil. The seal swellers will slow down the leak for a while by making the seals softer and swell slightly. Try it if re torquing the gaskets don't help.

Have changed the oil to Valvoline 20w50 VR1 with Lucas oil stabilizer, and already showing a lot of improvement. Will go for a 30 minutes drive tomorrow and test real improvements.
Some years ago I put some of that BlueDevil rear main seal repair in my son's beater Honda and it actually stopped his leaking seal.

[68WarDog]

Well to follow up on my rear main seal leak, I was a bit skeptic , but as of today the leak has stopped . 5 quart 20w50 with 1 quart of Lucas oil stabilizer and 8 ozs. of Blue Devil rear seal repair.. Possibly 60 total miles. 50 psi hot idle. 70 running .

[1968GTO421]

Originally Posted by 68WarDog

Well to follow up on my rear main seal leak, I was a bit skeptic , but as of today the leak has stopped . 5 quart 20w50 with 1 quart of Lucas oil stabilizer and 8 ozs. of Blue Devil rear seal repair.. Possibly 60 total miles. 50 psi hot idle. 70 running .

Have a leaky rear seal myself and need to do a temporary fix until my rebuild fund matures. Your fix sounds good to me.

Curious; did you re-torque oil pan bolts as part of fix?

[Tom Vaught]

I personally like 15W 40 oil (a Pennsoil) not a offshore oil.
Very happy with it after all of these years.

Tom V.

[78w72]

Originally Posted by 68WarDog

Well to follow up on my rear main seal leak, I was a bit skeptic , but as of today the leak has stopped . 5 quart 20w50 with 1 quart of Lucas oil stabilizer and 8 ozs. of Blue Devil rear seal repair.. Possibly 60 total miles. 50 psi hot idle. 70 running .

chances are it wasnt the oil weight that stopped the leak, it was the thick lucas stabilizer &/or the BD stop leak. i used to run the lucas & tried a couple stop leak products in a 4.0 jeep engine i owned that are notorious for rear main leaks & even with the 5 or 10/30 the engine uses they stopped or greatly slowed the leak.

[68WarDog]

Originally Posted by 1968GTO421

Have a leaky rear seal myself and need to do a temporary fix until my rebuild fund matures. Your fix sounds good to me.

Curious; did you re-torque oil pan bolts as part of fix?

After inspection there were no other detectable oil leak areas. Not quite sure if it was the increase in oil viscosity or the Blue Devil, just thankful no more leaking at this time

[grandam1979]

That’s awesome I’m surprised it stopped I learned something new.

[68WarDog]

Originally Posted by Tom Vaught

I personally like 15W 40 oil (a Pennsoil) not a offshore oil.
Very happy with it after all of these years.

Tom V.

Tom before changing over to 20w50 Amsoil synthetic, I had been running 10w40 Castrol, it leaked a little because of not filling the antirotation holes. The Amsoil made the leaking worse. May go back to the Amsoil in the spring.

[68WarDog]

Originally Posted by grandam1979

That’s awesome I’m surprised it stopped I learned something new.

So far so good