Best oil for 1968 Z28?

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steball

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I recently purchased a 68 Z28 RS numbers matching. I've heard several opinions on the best oil to use. There ha always been a little leak from the rear main seal. I tried Royal Purple 10-50 and the rear seal started leaking more than usual. Shoul I install 10-30 or 10-40 that might slow the leak. Also should I add some main seal stop leak to the oil? I really don't want to change the overall integrity of the motor. Thank you for any help.

-steball
 
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Give it a steady diet of Valvoline HM 10W-30 or Pennzoil HM 10W-30 and hope for the best. The HM stuff won't work miracles overnight, but over time it can slow some leaks significantly. Certainly won't hurt to try anyway...
 
T5 15W40 for an old SBC like that.

You should really just do the RMS on a car like that. Stop leaks are for cars that aren't worth fixing.

1968 RS/Z28....a car that dreams are made of. Pics please!
 
The RP likely cleaned a false seal maybe new motor oil will help the real seal regain some give after it dried out but in all likelihood you need to replace nit.
 
You are gonna want to use an oil with zinc to protect that cam. I suggest either Valvoline VR1, Amsoil Z-Rod, Royal Purple HPS,or Redline. All in 10w30.
Change your oil every 3K or once a year, whichever comes first. BTW 10w50 is too heavy. Don't buy into that thick oil stuff. 50w oil is okay for a 454. And stay away from Lucas HotRod. It contains way too much zinc and that can do more damage than good.
 
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I'd not worry too much about that leak. An old small block Chevy with cork oil pan gaskets, cork valve cover gaskets, and a rope rear main is going to leak. For "non spirited" driving, a solid moderate zinc oil like vr1 in straight 30 would be my pick. If you put it in the wind pretty often, vr1 in 20w-50, or similar oils like Kendall competition would be a good choice. Both oils have 1200-1400 ppm zinc and 1190-1300 phosphorus, and are pretty easily attainable and reasonably priced.
 
I'd use Castrol 0w40 or M1 0w40 from walmart. High enough HTHS for those engines, and very high performance. Then add 1/4 bottle of Redline Break In Oil Additive, you don't need much to boost the ZDDP level using this. It'll last 4 oil changes, and 1/4 bottle (1/2 cup) raises ZDDP by about 500 ppm, plenty enough with the Castrol or M1 0w40, in a 5-quart sump.
You could try a seal sweller. Not sure if it would work, but there is https://barsleaks.com/product/concentrated-rear-main-seal-repair/ to try.
 
Originally Posted by elpcmaster
You are gonna want to use an oil with zinc to protect that cam. I suggest either Valvoline VR1, Amsoil Z-Rod, Royal Purple HPS,or Redline. All in 10w30.
Change your oil every 3K or once a year, whichever comes first. BTW 10w50 is too heavy. Don't buy into that thick oil stuff. 50w oil is okay for a 454. And stay away from Lucas HotRod. It contains way too much zinc and that can do more damage than good.

Good advice. I second this. And other posters are correct, HM oil will not help a two piece rope rear main seal.
 
Listen to the advice about high-zinc and phosphorus oils - this is an engine that NEEDS them to survive.

The new Rotella T6 full-synthetic 15w40 would be perfect for this engine. It really would.

Would love to see pics of this beast!
 
If it truly IS a 302, yes, you are going to need some kind of high zinc oil.

If you are mechanically inclined, I would just replace the rear seal. You'll have to loosen and remove the motor mount bolts to raise the engine a few inches, but it's not really that hard on a Camaro.
 
Originally Posted by 69Torino
Originally Posted by elpcmaster
You are gonna want to use an oil with zinc to protect that cam. I suggest either Valvoline VR1, Amsoil Z-Rod, Royal Purple HPS,or Redline. All in 10w30.
Change your oil every 3K or once a year, whichever comes first. BTW 10w50 is too heavy. Don't buy into that thick oil stuff. 50w oil is okay for a 454. And stay away from Lucas HotRod. It contains way too much zinc and that can do more damage than good.

Good advice. I second this. And other posters are correct, HM oil will not help a two piece rope rear main seal.


There's also Brad Penn oil and Joe Gibbs Driven oil.
 
If you can afford a 1968 z28 matching numbers car then you can afford to fix it right....new rear main seal! Only 602 sold in 67 and 7,199 in 68. After that I would run Valvoline Vr1. Pics would be nice.
 
Originally Posted by addyguy
Listen to the advice about high-zinc and phosphorus oils - this is an engine that NEEDS them to survive.

The new Rotella T6 full-synthetic 15w40 would be perfect for this engine. It really would.

Would love to see pics of this beast!



Oh yeah why did the family of motors make it out of 68 with API SC motor oils with comparable ZDDP levels and less antiwear additives then today?
 
VR-1 is great stuff, and I would use 10w-30 in that engine. 30 weight oil is perfect for a small block. I have used Rotella T5 10w-30 and Valvoline VR-1 10w-30 in my big cam/heavy valvespring Fords many times with great success, especially on the dragstrip.
 
Originally Posted by dave1251
Originally Posted by addyguy
Listen to the advice about high-zinc and phosphorus oils - this is an engine that NEEDS them to survive.

The new Rotella T6 full-synthetic 15w40 would be perfect for this engine. It really would.

Would love to see pics of this beast!



Oh yeah why did the family of motors make it out of 68 with API SC motor oils with comparable ZDDP levels and less antiwear additives then today?


It was a small miracle if iron V8's lasted 100k without a valve job or wiping out a cam in the 60's, 70,s and early 80's. So they didn't really "last" by today's standards. We are enlightened people with modern technology on our side. We should capitalize on that.
 
I'd go with Brad Penn 10W-30 or 10W-40. I think it's called Penn Grade 1 since DA took over. The original green oil. No better price than Driven. Reasonable at Amazon or eBay. Better if u can find local seller. Or Schaeffer Racing if u can find local seller not Amazon. Way too $$$. Want ZDDP for flat tappets
 
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