check out AMSoil.  There is one for hotrods with zinc.  That's what I am using.

 I hear guys talk about Chevron RM Delo oil for diesels. It still contains zinc.

My local autozone stocks a zinc additive produced by Shell........it's in a metal retro looking Shell can. 

TKOPerformance wrote:

I would not run synthetic in an older engine, especially one that's sat for that long.  You are almost guaranteed to develop leaks.  Synthetics are vastly superior to conventional oil in terms of lubricity and thermal handling and stability.  That said some of those heavier hydrocarbons in the conventional oil serve to keep old seals pliable and thus prevent leaks.  In a fresh engine, after its been broken in, synthetic is the way to go.

I would recommend a 10W30 weight wise.  

I'm familiar with synthetic oil put into older airplane engines. They tend to plug up the ports and galleys and quit when you don't want them to. There are a few oils advertised that they are mineral oil with zinc already added to it. In airplane talk mineral oil is the same as breakin oil. Is that the case here or does that mean it is just petroleum oil? I don't want to continue to run breakin oil without a detergent in it. If I need to buy today's current oil off the shelf how much zinc additive do I put in it? I guess the container would say but askin anyways. 

You should run the viscosity range the manufacturer of the engine recommended. If it is a late 60’s engine and Ford recommended 10W-30, then run 10W-30. The additive package is determined by the camshaft lifters. Roller lifters get a late model oil with a late model additive package. Flat lifters need ZDDP. You can go to your local autoparts store and get the counter guy (or girl) to show you the three or four brands of ZDDP additive they stock. Blend the ZDDP according to the instructions on the ZDDP bottle. This is no time for you to pretend you are a chemist. I like to mix the additive and the new oil in a bucket prior to putting it in the engine to make sure the additive is mixed in evenly.

There are several current oil companies the sell an oil with sufficient levels of ZDDP for flat lifter camshafts: Amsoil, Royal Purple, Red Line, Joe Gibbs (very expensive), PennGrade 1. The advantage of these premixed oils is that they have already done all the lab testing for you, no test tubes needed. I have used Amsoil (a lot), Royal Purple, and Joe Gibbs. They all worked just fine.

One drawback to using an oil meant for current production engines is that their additive packages contain much more effective detergents than were used back in the 60’s. Today’s oils will remove built up sludge from an old engine, sometimes causing pluggage of oil passages. A buddy and I ran a test a number of years ago to see if the high detergent oils would clean up a sludgy engine. We bought a 65 Galaxie with a 352 that had so much sludge in the engine that you couldn’t get your finger in the add-oil port. We had to bore a hole in the sludge to change the oil. In went 5 quarts of high detergent and a new motorcraft filter. We ran the engine at 2000rpm, keeping an eye on the temp gauge and the oil pressure gauge. At about 45minutes the oil pressure fell and we shut it off. We let the engine cool for a couple of hours before we pulled the oil change plug. When the plug came out, no oil came out. We pulled the pan and found it full of black, stinky gel. We turned the pan upside down and nothing fell out. We cut the oil filter apart and found it full of the same black gel. We discussed cleaning out the pan and refilling with more high detergent oil, but we finally realized the oil passages were probably full of the same gel and would probably not clear out on a cold start. We tore the engine down (which was our ultimate goal from the beginning) and had the block and heads hot tanked. The machine shop charged us extra for the extra goop they had to clean out of their hot tank. Ah, the good old days where blocks and heads were real iron and hot tanks used real chemicals. This is admittedly an extreme example, but the 60’s oils would sludge up an engine. We heard a story that the previous owner of our Galaxie never changed the oil, he just added when it got low. Sadly, I met several people over the years that had the same philosophy

Synthetic oils are all derived from petroleum base stock just like conventional oils.  The difference is that these oils only contain one or two specific molecule types, whereas conventional oils contain dozens.  The synthetic is therefore targeted to meet very specific criteria very precisely.  Conventional oil meets it by having enough of the various "good" molecules to negate the effects of the "bad" molecules to allow it to meet the spec.  Obviously this also means the two oils have very different additive packages.  There are books written on the chemistry of oil (pretty fascinating subject actually), and its beyond what I can go into here, but consider that oil weight for example can be achieved through two or three different methods.  This can result in some engines with oil going in at a 40W and testing as 30W after a few hundred miles due to a phenomenon known as "oil shearing".  Then the debate ensues, do you just put 30W in the engine since the 40W turns into 30W anyway?  But the manufacturer must have known this an spec'd the 40W anyway, ...

If you have a carbed engine from the '60s with 300k on it I'd be seriously surprised.  You were lucky to get 100k from those engines.  The imprecise fueling provided by carbs washed the oil off the cylinder walls, especially when the engine was cold, and caused the rings and bores to wear out much faster than modern EFI engines.  The flat tappet cams were also a liability in that regard.  The way they were hardened the heat treatment typically didn't last more than 100k, and some of the lobes would be going flat by 100k.  Then you toss in the fact that the oil was bad back then, and the average person wasn't all that great about maintenance (nothing's changed there, just the engines have become more idiot proof and the oil's gotten better). 

Its not uncommon to see EFI engines with 200-300k or more on then that still have a ton of life left in them.  Both my wife's and my daily drivers have over 200k on them.  They both look a bit worse for the wear, but are mechanically perfectly sound.  That being said, I have had the heads off both engines for different reasons.  I've also done compression checks on both and both showed good compression even at that mileage.  It would be an extremely rare carbureted engine that would last anywhere near that long.  I've seen a handful over the years, but they were either built like a tractor (IH Scout) or maintained by a guy who treated maintenance like his job (Jeep Comanche).

I'd listen to Horman on this one too.  Pull the valvecovers off.  You'll be able to see how sludged up the engine is.  I too have seen them so packed full of sludge that the only clearance in there was from where the rockers had cleared a path.  I've seen lifter valleys where there was in imprint in the sludge of the bottom of the intake after it was pulled.  In part, the old oils contained a lot more heavy molecules like parafin that contributed to this.  There is machine shop and mechanic's lore that says certain oils like Quaker State were worse for this than others, but its hard to tell if that's true or urban legend.  In the end I think its less what oil was used and much, much more about how often it was changed.  Once an engine is that sludged up there's not much that can be done to clear it out short of a teardown.  Considering how bad being that sludged up is you have to know the bearings are shot anyway, so I'd rather tear it down and go through it rather than drive a time bomb. 

Here's one more fun fact about oil: Up until whaling was outlawed in the '70s ATF contained whale oil.  When the whale oil was removed automatic transmission failures went from 1 million annually to 8 million annually.  So engine oil back in the day seems to have been worse, yet ATF seems to have been better...

TKOPerformance wrote:

Synthetic oils are all derived from petroleum base stock just like conventional oils.  The difference is that these oils only contain one or two specific molecule types, whereas conventional oils contain dozens.  The synthetic is therefore targeted to meet very specific criteria very precisely.  Conventional oil meets it by having enough of the various "good" molecules to negate the effects of the "bad" molecules to allow it to meet the spec.  Obviously this also means the two oils have very different additive packages.  There are books written on the chemistry of oil (pretty fascinating subject actually), and its beyond what I can go into here, but consider that oil weight for example can be achieved through two or three different methods.  This can result in some engines with oil going in at a 40W and testing as 30W after a few hundred miles due to a phenomenon known as "oil shearing".  Then the debate ensues, do you just put 30W in the engine since the 40W turns into 30W anyway?  But the manufacturer must have known this an spec'd the 40W anyway, ...

If you have a carbed engine from the '60s with 300k on it I'd be seriously surprised.  You were lucky to get 100k from those engines.  The imprecise fueling provided by carbs washed the oil off the cylinder walls, especially when the engine was cold, and caused the rings and bores to wear out much faster than modern EFI engines.  The flat tappet cams were also a liability in that regard.  The way they were hardened the heat treatment typically didn't last more than 100k, and some of the lobes would be going flat by 100k.  Then you toss in the fact that the oil was bad back then, and the average person wasn't all that great about maintenance (nothing's changed there, just the engines have become more idiot proof and the oil's gotten better). 

Its not uncommon to see EFI engines with 200-300k or more on then that still have a ton of life left in them.  Both my wife's and my daily drivers have over 200k on them.  They both look a bit worse for the wear, but are mechanically perfectly sound.  That being said, I have had the heads off both engines for different reasons.  I've also done compression checks on both and both showed good compression even at that mileage.  It would be an extremely rare carbureted engine that would last anywhere near that long.  I've seen a handful over the years, but they were either built like a tractor (IH Scout) or maintained by a guy who treated maintenance like his job (Jeep Comanche).

I'd listen to Horman on this one too.  Pull the valvecovers off.  You'll be able to see how sludged up the engine is.  I too have seen them so packed full of sludge that the only clearance in there was from where the rockers had cleared a path.  I've seen lifter valleys where there was in imprint in the sludge of the bottom of the intake after it was pulled.  In part, the old oils contained a lot more heavy molecules like parafin that contributed to this.  There is machine shop and mechanic's lore that says certain oils like Quaker State were worse for this than others, but its hard to tell if that's true or urban legend.  In the end I think its less what oil was used and much, much more about how often it was changed.  Once an engine is that sludged up there's not much that can be done to clear it out short of a teardown.  Considering how bad being that sludged up is you have to know the bearings are shot anyway, so I'd rather tear it down and go through it rather than drive a time bomb. 

Here's one more fun fact about oil: Up until whaling was outlawed in the '70s ATF contained whale oil.  When the whale oil was removed automatic transmission failures went from 1 million annually to 8 million annually.  So engine oil back in the day seems to have been worse, yet ATF seems to have been better...

​Way back when I replaced the first 289 at 200k miles because I thought that was a good time to do it.  It was probably worn out.  I grew up with flatheads that were done before 100k miles.  I sold it to a guy who installed it in a BMW!  ( Don't ask).  Several years later, I ran into him again.  He still had the car and loved the engine.  No oil burning and plenty of power.  I changed oil every 5000 miles because multiples of 5000 are easy to remember.  Oil was 30w; whatever good brand I felt like buying.  Filter was usually a Ford FL-1.  So those engines could last a long time if properly taken care of.

​Now since I do not drive it as much, I change oil every 6 months because it is easy to remember the schedule.  Now I use 10w-30; whatever brand hits my fancy.  Filter is whatever fits.  It was installed in '89 and still has over 160psi in every cylinder with all being within 5 lb.  Oh, I just passed 100,000 miles on it, and there is another 289 I between.

​Take care of your car and it will take care of you.
 

So I'm looking at the oil filters on the Summit site and see the that the oil filters have all sorts of different specs as to what pressure the relief valve opens. 8 lbs to 22 lbs are the specs on the filters I was looking at. Why do they open so low? The oil pressure on my engine shows right at the top of the gage. It seems like I am not getting full filtering. Am I right?