Mixing VR1 synth with 5w40 euro

[PanteraMan74]

Hello everyone, this is my first post here so apologies if it’s in the wrong area.

I’m looking to run a summer oil blend next year of 4qts 5w40 euro valvoline and 3qts of synthetic VR1 20w50 which would theoretically give me an approximate 9w44 viscosity. The car is a 1974 Pantera with a 427 Windsor that I did not build but I would assume has bearing tolerances of .0027-.0030 because the builder calls for 10w40 oil. It’s 10.5:1 with a large cam in it. Makes about 550hp and I drive it very hard. I am unable to reach the engine builder for reasons I can’t exactly explain.

Is it safe to blend these oils together? According to a brand new Bosch mechanical gauge it currently makes 55psi idle pressure At operating temp and quickly bumps to 60psi at 2000rpm. The pump appears to be bleeding at 60psi because it doesn’t increase much from there.

This car has some heat soak issues despite the enormous radiator it has, I have no oil cooler. So for summer heat I am looking into running a blend.

 

[Astro14]

It will theoretically give you a 10W40. Or a 10W50. The viscosities are discrete but they cover a big range.

Don’t overthink this. Mixing doesn’t give you any advantages over simply choosing one of them.

Is it safe to mix them? Yes.

Is it the best way to go? Maybe not. The additive chemistry should be similar and will be compatible, but depending on what performance objectives you’re trying to meet, choose the one that makes more sense and just use that one.

In your case, with that high of an oil pressure, I would simply choose the Euro and call it good.

If, when the oil gets hot, you experience lower than desired pressure, you could switch to the VR1. I would use the old rule of 10 PSI/1,000 RPM. If the oil sustains that, it’s thick enough.

 

[kschachn]

It will theoretically give you a 10W40. Or a 10W50. The viscosities are discrete but they cover a big range.

Don’t overthink this. Mixing doesn’t give you any advantages over simply choosing one of them.

Is it safe to mix them? Yes.

Is it the best way to go? Maybe not. The additive chemistry should be similar and will be compatible, but depending on what performance objectives you’re trying to meet, choose the one that makes more sense and just use that one.

In your case, with that high of an oil pressure, I would simply choose the Euro and call it good.

A good answer.

 

[JavierH19]

It's safe but not preferred. I'd mix those two only once just to use up oil that would otherwise sit.

40 grade in minimum but not max, you can use 50 grade. But after using that blend use Mobil 1 15w-50.

You could also use Full Synthetic 15w-40 like delvac extreme, delo xsp, valvoline heavy duty. I'd skip rotella for it.

 

[97prizm]

Is there a Pantera forum that would have good insight?

 

[OVERKILL]

It's a Windsor, it doesn't need insane levels of ZDDP. Also, if you are basically on the pump relief at idle, you are running too heavy an oil, the engine is built really tight, or you have way too much oil pump (or a combo of those factors). A healthy Windsor with stock clearances (not tolerances) and a stock pump will run about 32-38psi hot at idle and be on the relief (~60-65psi) around 3,500rpm IIRC.

I echo @Astro14's advice, just run the Euro oil, no need for the VR1.

 

[burbguy82]

Makes about 550hp and I drive it very hard.

unadulterated power not computer controlled.....I would run VR1.

 

[PontiacHO]

If this isn’t a roller cam engine then definitely VR-1. Swinging a 4 inch stroke, making “500 horsepower “ and obviously high pressure valve springs, I’d be inclined to run an oil intended for a high performance old school V8…VR-1. Attempting extended oil change intervals with this engine is like driving this car like a Ford Pinto. You’re not going to do that!

 

[BiggerBreakerBar]

Mixing oils yields the best qualities of each.
Mixing oils yields the worst qualities of each, with the added unknown of compatibility.
Somewhere in between.

Chose 1, good luck.

 

[altaylar]

I would advise against mixing.

 

[Hohn]

Hello everyone, this is my first post here so apologies if it’s in the wrong area.

I’m looking to run a summer oil blend next year of 4qts 5w40 euro valvoline and 3qts of synthetic VR1 20w50 which would theoretically give me an approximate 9w44 viscosity. The car is a 1974 Pantera with a 427 Windsor that I did not build but I would assume has bearing tolerances of .0027-.0030 because the builder calls for 10w40 oil. It’s 10.5:1 with a large cam in it. Makes about 550hp and I drive it very hard. I am unable to reach the engine builder for reasons I can’t exactly explain.

Is it safe to blend these oils together? According to a brand new Bosch mechanical gauge it currently makes 55psi idle pressure At operating temp and quickly bumps to 60psi at 2000rpm. The pump appears to be bleeding at 60psi because it doesn’t increase much from there.

This car has some heat soak issues despite the enormous radiator it has, I have no oil cooler. So for summer heat I am looking into running a blend.

Just run the 20w50. In the summer it’s not going to cause any problems. Heck, it won’t cause any issues down to freezing temps. Don’t over think this. The real world difference between them isn’t enough to sweat. Certain not enough to undertake the bad idea of mixing.

 

[facility1]

you should be able to mix these oils together, just keep oci rather short,,also maybe you should run a more specific oil like Royal Purple HPS or Torco, Amsoil or other brands up to the job at hand, ,stay with a 10w-40 as the engine builder may know best on viscosity.

 

[OVERKILL]

you should be able to mix these oils together, just keep oci rather short,,also maybe you should run a more specific oil like Royal Purple HPS or Torco, Amsoil or other brands up to the job at hand, ,stay with a 10w-40 as the engine builder may know best on viscosity.

I'd make no assumptions about the builder given that it appears to be almost on the pump relief at hot idle, which is counter-productive and sounds like it's pretty tight with an HV pump jammed in there. From a power density perspective, I'm going to assume the "550HP" is likely engine dyno (SAE GROSS) and optimistic when compared to modern SAE NET ratings. We also don't know if it's roller or flat tappet, but 1.29HP/ci isn't, IMHO, "we need specific oil" territory, it's pretty close to stock 392 SAE NET output.

You can buy a 543HP 427 right from FRPP:
https://performanceparts.ford.com/part/M-6007-Z2427FRT

Roller cam, 10.5:1 compression.

Ford recommends 10W-30 or 10W-40 and says it should have 40psi hot, at 4,000RPM.

 

[RDY4WAR]

I would be slightly concerned with additive clash given the friction modifiers used in the synthetic version of VR1. I wouldn't blend it. Synthetic VR1 20W-50 is a rather good oil. I would run it exclusively. The 50 grade may cost you 0.5-1% power compared to a 5W-40.

Alternatively, for not much more than synthetic VR1, there's High Performance Lubricants HDMO 5W-40 with ~1200 ppm ZDDP, ~800 ppm moly, and strong detergent package in a robust base oil blend with ester and AN for cleaning. It will also go twice the interval of VR1 with relative ease.

 

[GR_CoB]

If you already have both on hand - mix, no problem.
But don't go out of your way buying separate oils to make the mix. It would be more beneficial to run separately. A rule that I learned is - mixing oil does not give you best of both worlds, it simply gives you a combination of weakened formulations. Neither one can perform at 100%, but they'll do good enough for a short OCI.

 

[PanteraMan74]

If you already have both on hand - mix, no problem.
But don't go out of your way buying separate oils to make the mix. It would be more beneficial to run separately. A rule that I learned is - mixing oil does not give you best of both worlds, it simply gives you a combination of weakened formulations. Neither one can perform at 100%, but they'll do good enough for a short OCI.

The problem is I do have both on hand. 6qts of each. I was planning on doing this mix during the summer months and 5w40 in colder months. As long as it is safe to mix the oils I intend to do it.

 

[PanteraMan74]

I would be slightly concerned with additive clash given the friction modifiers used in the synthetic version of VR1. I wouldn't blend it. Synthetic VR1 20W-50 is a rather good oil. I would run it exclusively. The 50 grade may cost you 0.5-1% power compared to a 5W-40.

Alternatively, for not much more than synthetic VR1, there's High Performance Lubricants HDMO 5W-40 with ~1200 ppm ZDDP, ~800 ppm moly, and strong detergent package in a robust base oil blend with ester and AN for cleaning. It will also go twice the interval of VR1 with relative ease.

What exactly is the concern with the clash of friction modifiers?

 

[PanteraMan74]

If this isn’t a roller cam engine then definitely VR-1. Swinging a 4 inch stroke, making “500 horsepower “ and obviously high pressure valve springs, I’d be inclined to run an oil intended for a high performance old school V8…VR-1. Attempting extended oil change intervals with this engine is like driving this car like a Ford Pinto. You’re not going to do that!

It is a full roller engine.

 

[Japanese]

As long as it is safe to mix the oils I intend to do it.

Just use 5W-40 when cold and 20W-50 in the summer.
What is your concern? Are you afraid to run 20W-50 because the builder recommended 10W-40?
Then first try to sell the 20W-50 before mixing it or just return it at Walmart for store credit and buy the oil you want.

 

[RDY4WAR]

What exactly is the concern with the clash of friction modifiers?

Synthetic VR1 uses 2 particular friction modifiers in synergy. They complement one another. It's a pairing that's worked well in racing formulas of the past and now made it's way into VR1. Introducing another FM has a high potential of disrupting that synergy, causing the FMs to compete against one another rather work together. Thus, blending it with another oil would give worse results than either one used exclusively.

Given that it's a roller engine, that changes this discussion since additional ZDDP is not required. If you want something off the Walmart shelf, I'd use an ACEA A3/B4 spec 5W-40 such as Mobil 1 FS Euro 5W-40 or Pennzoil Platinum Euro 5W-40. If you don't mind spending more for better quality, High Performance Lubricants PCMO 5W-40 or 10W-40 would be top shelf and run very clean.