Best oil for 1966 Pontiac GTO w/ new camshaft?

[Exit32]

I'm in the process of restoring a 1966 Pontiac GTO that is equipped with the optional 389-cubic-inch, 360-horsepower, Tri-Power engine.

This engine was rebuilt by a previous owner, and the cylinder bores, rings, and bearings are in good condition. However, the camshaft is incorrect for a Tri-Power engine, so I am installing the appropriate GM 9779068 camshaft with new hydraulic lifters.

I plan to use Crane Cams Super Moly Assembly Lube to coat all the cam lobes and lifter surfaces before assembly. I will also spin the oil pump with an electric drill to build oil pressure before starting the engine, and I know enough to run the engine at a fast idle for the first 20-30 minutes to make sure the cam is getting plenty of oil during break-in.

My question for those in the know here is, what motor oil would you recommend for the initial break-in period and what motor oil is recommended when it's time to drive this beauty to car shows and cruise nights? Also, do I need a ZDDP additive like ZDDPlus because this is a flat-tappet engine?

I'm thinking maybe Rotella 10w-30 or even Rotella T5 10w-30 would be appropriate.

FWIW, here are the specs for the new GM 9779068 camshaft:

- Intake duration @ .050" lift: 212
- Exhaust duration @ .050" lift: 225
- Intake lift w/ stock 1.5 ratio rockers: 0.408"
- Exhaust lift w/ stock 1.5 ratio rockers: 0.407"

Your opinions and guidance are much appreciated!

 

[Rock_Hudstone]

With a flat tappet you want something with the most ZDDP you can get, and not just for break in either.

These days that means a heavy duty diesel oil in the older CI-4 grade, (the new CJ-4 grades are way down on ZDDP levels). A good off the shelf oil that fits the bill is Castrol GTX 15w-40, it's still available at Advance Auto parts in CI-4 grade last time I checked and has a healthy dose of Zn & Ph levels.

I'd also suggest adding container of GM E.O.S engine oil supplement to the oil. Its loaded with ZDDP and can be used as regular additive to the crank case.

http://www.gmpartsdirect.com/results.cfm

 

[Lyman]

For cam break in I always rev @ 2k for 20 minutes. Watch the temp gauge and set the final timing afterward. Nothing worse then a cam going bad due to not being broke in right. I agree with the diesel oil recommendation.

 

[fxrider]

Valvoline VR-1 20W50

 

[Rock_Hudstone]

Working link for the E.O.S.

http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=EOS

I'd pass on ZDDPplus, a little too much in my opinion. The E.O.S is a better supplement and has been around long time.

 

[artificialist]

I'd rather buy RP Break in oil, because it was built just for this purpose only.

 

[mechanicx]

Nice car. the mid-60s GM intermediates are my favorite classic cars. I think you are on the right track. You'd be wise to use a higher zddp 10W30 like Rotella. I think if you are using an OE cam, lifters and valve spring rate, then the Rotella should be sufficient for break in and regular use. I think Rotella still has over 1000-1200 ppm of zinc/phosphorus.

 

[Bluestream]

I would just add some GM EOS. Its the best there is for new cams

 

[Chris142]

That hipo 389 will have pretty stiff valvesprings. I'd go with a break in oil for sure. Maybe even add one of the break in addatives too.

Once broken in it will still need lots of ZDDP. Definatly don't use run of the mill oils in it.

 

[NHGUY]

HDEO 10W30? Rotella?
The 66 Tempest/LeMans/GTO is the pick of the 66 GM A-body.They did so much better with that body than Buick,Olds or Chevrolet.It looks right....its sleek,long looking,very much "complete",the 66-67 Olds Cutlass/F85 looks horribly overblown and mishapen and the Buick very bland with little to no character.The Chevy somewhere in between.Why all 66 GM midsize sales didnt go to Pontiac by default is a huge mystery.

 

[Rock_Hudstone]

Originally Posted By: mechanicx
I think you are on the right track. You'd be wise to use a higher zddp 10W30 like Rotella. I think if you are using an OE cam, lifters and valve spring rate, then the Rotella should be sufficient for break in and regular use. I think Rotella still has over 1000-1200 ppm of zinc/phosphorus.

Rotella 10w-30 is a great oil no doubt but it falls a little short for a flat tappet engine break in. Zinc levels are slightly below the desired 1200+ ppm. Same goes for the 20w-50 VR-1

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1791357#Post1791357

Can't remember what exactly the Castrol 15w-40 GTX VOA was but I think it was pushing 1300pp Zn, with an equally high Ph.

 

[TFB1]

Anybody notice the miniscule valve lift(at least by today's stds)??? Even stiff springs aren't going to be placing a extreme load on the lifters and cam lobes...

 

[Rock_Hudstone]

Originally Posted By: TFB1
Anybody notice the miniscule valve lift(at least by today's stds)??? Even stiff springs aren't going to be placing a extreme load on the lifters and cam lobes...
Its a long duration low lift cam for sure, but it doesn't take much to wipe out a cam these days.

Passenger car motor oil circa 1966 had tons of ZDDP. Even up to 1995 API SG grade oil had 1200-1300 ppm, its been down hill ever since, the curent API SN grade is a pathetic 600 ppm average.
All done in the name of "global warming".

 

[Exit32]

Thanks for all the excellent input and opinions here. I'll definitely invest in a bottle of GM E.O.S. engine oil supplement and will do my research to identify a high-ZDDP oil for my little GTO.

A few years ago, I thought I did everything right with a new camshaft in a Ford 427 side-oiler, but I wiped out a lobe and lifter within a hundred miles. Installed a new Crower bump stick and used Castrol GTX 20w-50 to break it in, then Mobil 1 15w-50 since then without issues.

 

[Highline9]

Thats a mild cam as far as lobe intensity. Any HDEO should be ok. When lift starts going over .500 worry. Whats your closed and open valve spring pressure?

 

[mechanicx]

Originally Posted By: TFB1
Anybody notice the miniscule valve lift(at least by today's stds)??? Even stiff springs aren't going to be placing a extreme load on the lifters and cam lobes...


I agree. It's a factory cam designed to break in without the luxury of special break-in procedures and to last many thousands of miles. I don't think SAE service rated motor oil ever had much more than 1000-1200 ppm zinc even back in the day. I know I read some material that suggested 1000-1200ppm was sufficient for factory cams. You would use HDEO with short OCI of about 3k miles/3 months to make sure the sacrificial zddp doesn't get depleted to low. But you would want shorter OCI anyway with a carbureted egine.

 

[Merkava_4]

PM sent!

 

[OVERKILL]

Originally Posted By: mechanicx
Nice car. the mid-60s GM intermediates are my favorite classic cars. I think you are on the right track. You'd be wise to use a higher zddp 10W30 like Rotella. I think if you are using an OE cam, lifters and valve spring rate, then the Rotella should be sufficient for break in and regular use. I think Rotella still has over 1000-1200 ppm of zinc/phosphorus.



This.

It isn't a "wild" aftermarket stick.

 

[paulswagelock]

American Refining makes both a break in oil specific for this, and high performance oils specific for older cars. Good reputation with the classic car gurus. Great customer service for questions, sending data, even doing a free analysis to prove other lab errors. Look into them as well. The oil is marketed as Brad Penn oils.

 

[A_Harman]

Originally Posted By: Exit32
Thanks for all the excellent input and opinions here. I'll definitely invest in a bottle of GM E.O.S. engine oil supplement and will do my research to identify a high-ZDDP oil for my little GTO.

A few years ago, I thought I did everything right with a new camshaft in a Ford 427 side-oiler, but I wiped out a lobe and lifter within a hundred miles. Installed a new Crower bump stick and used Castrol GTX 20w-50 to break it in, then Mobil 1 15w-50 since then without issues.


I'm against using the GM EOS. It's low in zddp concentration compared to the available supplements such as ZDDPlus or Red Line Break-In. There are a few break-in oils out there by Royal Purple, Brad Penn, and Joe Gibbs. Or Red Line 30W race oil has a whole great, big boatload of zddp. Use one of those for break-in. Then go with Valvoline VR1 10w30 or a blend of VR1 10w30 & 20w50 if you feel like you need a 40-weight.