My father in law has a 66 Pontiac GTO with the 389 and a 4 speed. Last year he had the motor machined along with new pistons. He also had a frame off restoration done in 2012. Right now he's got Brad Penn 30 weight break in oil in it as per the machine shop that re did the engine. Some facts about the car:
He does about 500 to a 1000 miles a year
The engine is bored over 30 with a flat tappet cam
He only uses an AC Delco PF24 oil filter
He does change it about once a year
He likes Pennzoil 30 weight oil but it was used before the engine was re done.
My father in law isn't sure what to use but wants to use an oil that has zinc in it for the cam. The Brad Penn has been in there since last year and has the itch to change it. If anyone has a recommendation it would be greatly appreciated and thanks in advance, Steve.
Oil for 1966 Pontiac GTO
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Amsoil Z-Rod is made for just this situation. Plenty of zinc for your motor and extra anti-corrosion addatives for toys that aren't driven daily. Done.
Any B-I-L with a '66 GTO can't be all bad! 
+1 on Bandito440's plenty o' zinc recommendation.
+1 on Bandito440's plenty o' zinc recommendation.unless you want to pay 8 or 9 bucks a qt I would use mobil 0w40 myself.
Well I was in a similar situation with several gm vehicles I restored over the past few years. From my research here are a few oils out there with higher levels of zddp that will protect that flat tapped cam. Valvoline vr1 which is available in conventional and synthetic multi weights 10w30 and 20w50. The brad penn is available in most any weight u need. Mobil 1 high mileage 10w30 and 10w40 & mobil 1 15w50. Quaker state defy in 10w30 and 10w40 have the necessary zddp levels too. Most any hdeo "diesel oil" will work also but if it's freshly rebuilt so you probably don't need all the magnesium they contain. Amsoil z rod as previously mentioned is also a great oil. Why not just stick with brad penn if you can get it locally? Good luck with the car.
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Originally Posted By: Bandito440
Amsoil Z-Rod is made for just this situation. Plenty of zinc for your motor and extra anti-corrosion addatives for toys that aren't driven daily. Done.
Thank you everyone for the replies. I will throw the oils at him and let hime decide. He's had this car since he was 18 which he bought used and just wants to keep everything stock like he got it.
If its a stock cam you really don't need all that zinc you have to remember oil has came a long way since the 60's.Of course piece of mind would be a factor for me to
nce the cam is broke in you could probably get away with almost anything really depends on how deep his wallet is.Mobil 0w40 has over 1000ppm of zinc and its full syn which can be had for 25 bucks at WM.You could use just about anything and add 1/4 bottle of redline too.
nce the cam is broke in you could probably get away with almost anything really depends on how deep his wallet is.Mobil 0w40 has over 1000ppm of zinc and its full syn which can be had for 25 bucks at WM.You could use just about anything and add 1/4 bottle of redline too.Hi Droopy,
So many opinions, so much incorrect advice.
Engines with the type of work you've described require a good quality dino oil for break in, do NOT use a semi or full syn, a bit of friction is required for proper break in and seating of the surfaces. And please, you Amsoil psychos don't embarass yourselves by arguing.
Also, although there's nothing "Wrong" with using a straight weight oil like 30w, recall that they function best (i.e. lubricate most effectively)in a more limited range of ambient temperatures. So, unless you live and house the car where the temperature is really constant, there's no benefit..and probably a bit of a disadvantage to using straight 30w. Likewise, HD oils (like Rotella T and Delvac)are at their best in unopened vintage engines which perform best with the extra stuff in them.
The correct oil for you dad to use is (*GASP!*) ANY brand dino 10w-30 of his choice for at least a few years (@ 500-1000 mi/yr.) and probably forever, changed at least once a year, but no longer.
Originally Posted By: Noey
Hi Droopy,
So many opinions, so much incorrect advice.
Engines with the type of work you've described require a good quality dino oil for break in, do NOT use a semi or full syn, a bit of friction is required for proper break in and seating of the surfaces. And please, you Amsoil psychos don't embarass yourselves by arguing.
Also, although there's nothing "Wrong" with using a straight weight oil like 30w, recall that they function best (i.e. lubricate most effectively)in a more limited range of ambient temperatures. So, unless you live and house the car where the temperature is really constant, there's no benefit..and probably a bit of a disadvantage to using straight 30w. Likewise, HD oils (like Rotella T and Delvac)are at their best in unopened vintage engines which perform best with the extra stuff in them.
The correct oil for you dad to use is (*GASP!*) ANY brand dino 10w-30 of his choice for at least a few years (@ 500-1000 mi/yr.) and probably forever, changed at least once a year, but no longer.
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Once a year 500-1000 miles? LOL, I'd just use Quaker State Defy 10W-30 and not over think it....
Originally Posted By: Droopy
My father in law has a 66 Pontiac GTO with the 389 and a 4 speed. Last year he had the motor machined along with new pistons. . . . Right now he's got Brad Penn 30 weight break in oil in it as per the machine shop that re did the engine. . .
My father in law isn't sure what to use . . .
Indiana79 - what's the connection between freshly rebuilt and magnesium?
My Rotella 15W40 HDEO UOA had magnesium counts of 12 & 22. Is that high?
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I did not see the location where the car is ran, but I am also guessing that it is stored in winter? Shell Rotella T 15W-40 might be a good match for this engine if the climate permits and the zinc levels are adequate for the application.
Shell Rotella VOA
It's ran in New York where he only runs it from when the road salt is gone which is about early May until maybe mid October. He likes 30w Pennzoil yellow bottle but he's not sure it has enough zinc in it.
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