Don wrote:

Serf around on this site  Lots of tech answers.  I started a personnel quest using engineering analysis to find the BEST oil.  I've been on this Quest for 21 years (relax NOT full time )and haven't found anything better for cars than Amsoil. 
 https://www.amsoil.com/performance-tests/

so whats your take on 5w20

First, do not try to break in an engine on synthetic oil.  Use a specific break in oil and follow proper break in procedures.  Once broken in you can safely switch to synthetic.

Second, with a roller valve train there's no need to worry about zinc content.  Its absolutely essential for a flat tappet engine, but the points of contact which generate extreme pressure in a flat tappet engine don't exist in a roller engine.

Third, a typical 5.0 is going to be happy on 5W30.  5W20 didn't exist until the modular engine started using it.  Those engines have a really different oiling system than the old pushrod engines.  Could you run 5W20?  I'm sure you could.  Its a full synthetic (they don't make that weight in conventional), however its not really the ideal weight for that engine.  The oil is so good you probably wouldn't have any issues, but why risk it?
 

I am no oil specialist, but have traditionally run 10w40 in my classics. When I started using the 5.0 roller blocks and thinner low tension piston rings, I still used the same. However, you have got me thinking.  Why not use the same oil that a foxbody 5.0 or Explorer 5.0 would have used?  I may try the thinner oil in my 331, which is basically same design as a late model 5.0. 

I know on my 427, which has a roller cam and the thin rings, my oil pressure is marginal at idle using 10w40, so I doubt I would risk putting thinner oil in it.

I have disassembled many 5.0 roller engines from foxbody and Explorer.  A common problem that always exists is stuck piston rings. And those engines most likely always had the thinner oil in them.  That said, maybe a thicker oil would not be a good idea when retrofitting those engines in classic cars. If they stick using thin oil, I would imagine that issue would get worse with 10w40.  But, it may be more an issue of oil change frequency?  Who knows. I rarely have any history on core engines that I buy.

Just my rambling two cents on the issue.

Maybe roller cam engines with thin low tension rings can be perfectly happy on the modern thinner oils, and you might get a little better mileage and easier access to the oil you need.

From what I've found the oil grading that was used when our cars were new is now obsolete.  The current API standard equivalent oil for the classic Mustang is a 10W30 or a 5W30 depending on ambient temperature.  I've run 5W30 in my 289 for years now with no issue and reasonable oil pressure (30-35psi at idle, jumps to 60+ at redline).

The 5.0 roller engines were all spec'd as 5W30 from the factory.  I see no reason to switch.

Raymond on your 427 I'm wondering if that recommendation was based on the oil weight or the fact that 15W40 is a Diesel spec oil.  I've never seen that weight in a gas formulation.  The reason that's important is that Diesel oil continued to have the proper amount of ZDDP for at least a decade after it was removed form the gas formulation oils.  However, that didn't last and the current Diesel spec oils no longer have the high concentration of ZDDP, as all modern Diesels also have roller valve trains.  You still see some guys who don't know this claim there's benefit to running Diesel oil in your gas classic, but you're better off to just run the right weight and add something with ZDDP in it if you still have a flat tappet cam (I use STP).

As far as the super thin modern synthetics they probably would be fine if oil pressure remained acceptable.  I can tell you I know a couple guys who run a crate engine class at the strip.  Their big secret is to run only 2 quarts of 0W20 synthetic in the engine.  If you do the math the pan is dry by mid track, yet these engines go a whole season run like this without ill effects because the oil is go good, and they all have full roller valve trains, and coated bearings.  In racing you do what you have to do to win and stay legal.  I would never risk one of my street engines on this, or even with a full pan of the super light stuff.  I just don't see the trade off in benefit for the potential catastrophe. 

6sally6 wrote:

Y'all know my 'feelings' about oil (all comes outta the same hole...basically)
You already bought oil.....I'd use it. (maybe after the engine break-in)
Thin oil and thin rings are LESS drag(more HP+!) butt......doubtful you can 'feel it' it's so small.
Engine "runs cooler"... also so small.
"Saves gas"!!! ...prolly pretty tiny too!
Same deal with conventional oil vs synthetic!
Tiny difference especially on a basic street engine.
Big Sal sez.......RUN IT !!
6sally6

And realmustangsteve says DRIVE IT TO THE BASH!!!

MS wrote:

I am no oil specialist, but have traditionally run 10w40 in my classics. When I started using the 5.0 roller blocks and thinner low tension piston rings, I still used the same. However, you have got me thinking. Why not use the same oil that a foxbody 5.0 or Explorer 5.0 would have used? I may try the thinner oil in my 331, which is basically same design as a late model 5.0.

I know on my 427, which has a roller cam and the thin rings, my oil pressure is marginal at idle using 10w40, so I doubt I would risk putting thinner oil in it.

I have disassembled many 5.0 roller engines from foxbody and Explorer. A common problem that always exists is stuck piston rings. And those engines most likely always had the thinner oil in them. That said, maybe a thicker oil would not be a good idea when retrofitting those engines in classic cars. If they stick using thin oil, I would imagine that issue would get worse with 10w40. But, it may be more an issue of oil change frequency? Who knows. I rarely have any history on core engines that I buy.

Just my rambling two cents on the issue.

Maybe roller cam engines with thin low tension rings can be perfectly happy on the modern thinner oils, and you might get a little better mileage and easier access to the oil you need.

  

My explorer engine had 3 cylinders with stuck rings.   
 

My flat tappet engine with about 60,000 miles since the rebuild is stuck with 10W30. It seems to run fine and last mpg check, I am getting about 22mpg.

Raymond_B wrote:

MS wrote:

I am no oil specialist, but have traditionally run 10w40 in my classics. When I started using the 5.0 roller blocks and thinner low tension piston rings, I still used the same. However, you have got me thinking. Why not use the same oil that a foxbody 5.0 or Explorer 5.0 would have used? I may try the thinner oil in my 331, which is basically same design as a late model 5.0.

I know on my 427, which has a roller cam and the thin rings, my oil pressure is marginal at idle using 10w40, so I doubt I would risk putting thinner oil in it.

I have disassembled many 5.0 roller engines from foxbody and Explorer. A common problem that always exists is stuck piston rings. And those engines most likely always had the thinner oil in them. That said, maybe a thicker oil would not be a good idea when retrofitting those engines in classic cars. If they stick using thin oil, I would imagine that issue would get worse with 10w40. But, it may be more an issue of oil change frequency? Who knows. I rarely have any history on core engines that I buy.

Just my rambling two cents on the issue.

Maybe roller cam engines with thin low tension rings can be perfectly happy on the modern thinner oils, and you might get a little better mileage and easier access to the oil you need.

Just food for thought, but my build sheet from Fordstrokers for my 427w recommends 15w-40. Sadly I could not find VR1 in that so I ended up going with 10w-30 and I get around 30 psi at idle and 60 at WOT.
 

   

How do you like your Fordstrokers engine?   Did you buy a shortblock or there long block?   Thanks!
 

Raymond_B wrote:

Steve69 wrote:

How do you like your Fordstrokers engine?   Did you buy a shortblock or there long block?   Thanks!
 

LOVE it, it is a DART based Liberator longblock. So far (knock on wood) it has been great.
 

   Thanks for the info!