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Hey guys what would you recommend as the best oil to run in the AMC 327 Vigilante engine? Currently on 10W30 Pennzoil

I say anything but Pennzoil. Past that, what's your current oil pressure? I like 10w-30 for old American cast iron engines, but I'll go 10w-40 to keep pressure up before a rebuild. As for dino vs synthetic, keep with dino and 3000mile/3month intervals. Synthetic can buy time between changes in a modern engine, but old iron like these have too loose of tolerances to take advantage of it.

Regarding Penn/Quaker, it has nothing to do with "parafin". They make crummy oil and they know it. Rather than fix their formula, the created a damage control ad campaign around the fact that 100 years ago Penn oil had more parafin in the crude form than Texas. This has nothing to do with the sludge that Pennzoil has become synonymous with today. They even have the audacity to blame drivers for "driving wrong" to create the sludge. Valvoline, mobil1, Castrol, even Walmart supertech are all better oil.

Rotella 15-40. As stated, dump the Pennzoil.

I like the 15W40 Rotella or Delo, but I don't drive my Jeeps much in the winter. I used to run 20W50 Castrol in southern California where it rarely got as cold as 40F. IMO you'd want something with a lower viscosity for winter use where it gets cold, maybe 10W30. There are thinner oils like 0W20 and 5W30, but I believe those are only suitable for modern engines with roller tappets, and are more about fuel economy than longevity/durability. The diesel oils (like Rotella and Delo) are said to be better for older engines with flat tappets, and are suitable for both diesel and gasoline engines. Valvoline is also good IME.

Something 10w30 with zinc. All oils back then had zinc in them. These days very few oils do.

I run Valvoline in mine, but it’s a much newer engine. If I had an engine as rare as the 327, I would use Amsoil ZRod. Costs more, but will keep it safe.

I'd avoid zinc levels over 1200 ppm. Too much causes premature wear. Even in flat tappet engines, you are looking for shear protection. Zinc is an old myth I once believed as well. If you note, high zinc also usually states "for racing engines". Those engines are torn down at much more frequent intervals (usually every season). All oils now meet an API minimum spec guideline (symbol on bottle).

Many oils still have zinc and phosphorus, just a much lower concentration.

I'd avoid synthetics if the engine is original. As stated, tolerances will be worn, oil seals will not be the viton kind. Stick with dino stuff. I run Valvoline in my old vehicles (64 Belair and Jeep).

If a fresh rebuild with new seals and tight tolerances, I'd say mobil 5W30. My LS loves it.

I had a remanufactured 360 put in with flat tappet cam and for break in (after actual break in oil) have run Rotella 15w-40 with a zinc additive from STP, and changed the oil at 100 miles, 500 miles, and will again at 1500 miles of driving, but at 1500 miles of driving will not do the STP additive. At 3,000 miles, I'm going to switch to Valvoline VR1 10w-30 or 40.

You absolutely need zinc in flat tappet engines. it was only removed because it wasn't compatible with modern emission systems . ask any cam manufacturer.

There are lots of options but I run only Brad Penn oil. it used to be called Kendall and it's still the same high grade green PA oil with zinc and phosphorus added for flat tappets. you can buy it from Amazon or lots of places on line and it's not horrible priced.

440sixpack wrote:You absolutely need zinc in flat tappet engines. it was only removed because it wasn't compatible with modern emission systems . ask any cam manufacturer.

Not true. Any good oil worth it's weight will protect. flat tappets and other moving parts are protected by shear ratings. Flat tappets still exist today. Not every new car made has roller lifters.


https://540ratblog.wordpress.com/2013/0 ... t-ranking/


Do what you want, but I no longer subscribe to the zinc myth.
The 283 in my Belair had no special break in other than gentle driving. I run simple dino oils. No issues whatsoever.

Found this the other day. Thought it was pretty information and helpful.

https://www.cherokeeforum.com/f2/rotell ... ng-188168/

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dodgerammit wrote:

440sixpack wrote:You absolutely need zinc in flat tappet engines. it was only removed because it wasn't compatible with modern emission systems . ask any cam manufacturer.

Not true. Any good oil worth it's weight will protect. flat tappets and other moving parts are protected by shear ratings. Flat tappets still exist today. Not every new car made has roller lifters.


https://540ratblog.wordpress.com/2013/0 ... t-ranking/


Do what you want, but I no longer subscribe to the zinc myth.
The 283 in my Belair had no special break in other than gentle driving. I run simple dino oils. No issues whatsoever.

I cannot think of a single new car that has flat tappets. The VAST majority are overhead cams. GM and FCA make push rods V8's, but all of them have been full roller for ages.

I'm aware of no flat tappet engines today. if you have a worn low pro engine with valve spring pressures something like a wet noodle you can probably get by for a long time not believing in friction. for the rest of us we need to save our cams and lifters.

You'll find no cam manufacturer or half reputable engine builder who doesn't recommend or require zinc. Don't be a hero , just use it .

Stuka wrote:

dodgerammit wrote:

440sixpack wrote:You absolutely need zinc in flat tappet engines. it was only removed because it wasn't compatible with modern emission systems . ask any cam manufacturer.

Not true. Any good oil worth it's weight will protect. flat tappets and other moving parts are protected by shear ratings. Flat tappets still exist today. Not every new car made has roller lifters.


https://540ratblog.wordpress.com/2013/0 ... t-ranking/


Do what you want, but I no longer subscribe to the zinc myth.
The 283 in my Belair had no special break in other than gentle driving. I run simple dino oils. No issues whatsoever.

I cannot think of a single new car that has flat tappets. The VAST majority are overhead cams. GM and FCA make push rods V8's, but all of them have been full roller for ages.

Cam lobes actuate shims on valve stem buckets. Not exactly a flat tappet, but far from roller.

https://www.bobistheoilguy.com/forums/u ... /4777426/1

What is so funny is the amount of people that get so bent out of shape over the zinc debate, claiming you need high zinc for older engines. Modern oils have a higher zinc rating today (800-1000ppm), than in the 60s (600ppm).

You're entitled to your own opinion but not your own facts.

You need zinc. period. and you won't find it in standard modern oils. this is not a matter that's up to debate and I'm done with this silly conversation . if you're willing to trash your engine to save a couple bucks per oil change or prove a point be my guest but don't encourage others to do the same.

The debate is over and thread locked.