Valvoline Restore & Protect 5W30 OR Mobil 1 Euro FS 0W40?

[shepherm]

Nothing on the road spends most of its life at 7,000 RPM. In fact, most of the time, most engines are between idle and 3,500 RPM. Not really sure that your discussion of the hydraulic wedge characteristics is accurate. You are conflating hydraulic wedge characteristics with the weight of the oil and making the point that higher viscosities might provide better function at very high RPM. Then you are suggesting that higher viscosity oils won't function properly at lower operating temperatures because "a lot of the oil doesn't make it through the bearings." This might seem true, but the fact of the matter is that any oil between 0W8 and 20W50 will flow through the bearings of any internal combustion vehicle on the road without ill-effect.

Okay, I’m not sure where to start.

I didn’t say anything about road engines, I said engines. How many “road engines” call for 50 weight oil? Not many, however there are plenty of of engines that call for 50 weight oil if you track the car but 30 weight for the street. Why? Clearances don’t change just because it’s on the track, but RPM and oil temp does.

As for thicker oil in the bearings. Again, only so much oil will fit in the bearing clearance. The ticker it is the more that gets bypassed at the pump or squeezes out from the side of the bearings. The oil that squeezes out removes about half the heat that the oil that makes it around the bearings.

From a hydraulic wedge/metal to metal contact, it’s fine. Why? Because the the oil has the clearance full, so there isn’t going to be metal to metal. However, bearing design and oil viscosity calculations also has an oil volume rate TROUGH the bearings to cool the bearing. When the thick oil bypasses, at pump or squeezing out, the bearing temp will actually run hotter. This leads to bearing surface cracking.

I’m traveling right now and don’t have my bearings design books with me to quote it, however I’ll post a couple pictures I have. First is the graph that shows rate, temp and heat removed for a different rates for SAE 20 weight.
The next picture is K1 that also discusses oil flow rate and bearing temp. Same for the king bearing picture.

So again, there’s more to bearing design and viscosity than the simple rule of thumb or “thicker is better”.

 

[kschachn]

Okay, I’m not sure where to start.

I didn’t say anything about road engines, I said engines. How many “road engines” call for 50 weight oil? Not many, however there are plenty of of engines that call for 50 weight oil if you track the car but 30 weight for the street. Why? Clearances don’t change just because it’s on the track, but RPM and oil temp does.

As for thicker oil in the bearings. Again, only so much oil will fit in the bearing clearance. The ticker it is the more that gets bypassed at the pump or squeezes out from the side of the bearings. The oil that squeezes out removes about half the heat that the oil that makes it around the bearings.

From a hydraulic wedge/metal to metal contact, it’s fine. Why? Because the the oil has the clearance full, so there isn’t going to be metal to metal. However, bearing design and oil viscosity calculations also has an oil volume rate TROUGH the bearings to cool the bearing. When the thick oil bypasses, at pump or squeezing out, the bearing temp will actually run hotter. This leads to bearing surface cracking.

I’m traveling right now and don’t have my bearings design books with me to quote it, however I’ll post a couple pictures I have. First is the graph that shows rate, temp and heat removed for a different rates for SAE 20 weight.
The next picture is K1 that also discusses oil flow rate and bearing temp. Same for the king bearing picture.

So again, there’s more to bearing design and viscosity than the simple rule of thumb or “thicker is better”.

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Nevertheless any production engine can handle any SAE grade. Many engines operate in other countries with 70-grade oils. It won’t cause damage.

 

[notharry]

Yea...I said my piece. I have to be done talking about this. Very good points to consider. Peace

 

[ZeeOSix]

As for thicker oil in the bearings. Again, only so much oil will fit in the bearing clearance. The ticker it is the more that gets bypassed at the pump or squeezes out from the side of the bearings. The oil that squeezes out removes about half the heat that the oil that makes it around the bearings.

Journal bearings self pump less oil volume with thicker viscosity, all other factors held constant. The oil supply pressure also adds some more flow on top of the self pumping side leakage flow. So the total oil flow through the bearing is the summation of those two components. So any engine with a properly designed and sized PD oil pump is going to make the bearings have added side leakage above its natural rotational self pumping flow which will help them run cooler.

If xW-40 or xW-50 caused too much heat inside the journal bearings even with extended high RPM use like on the track, there would be a lot of damaged engines, but there isn't. And part of the reason is because even if they run a bit hotter with thicker oil, it's not enough of a temp rise to cause a problem. The higher HTHS viscosity will still provide more MOFT even with the slightly higher temp in the bearing.

As pointed out earlier, engines with very tight bearing clearance spec xW-40 (ie, many high RPM (10,000+) motorcycles and various hi-pro cars) and xW-50 oil (ie, Ford Coyote Track Pack, Roadrunner (Boss 302), Voodoo (GT350) & Predator (GT500) … 7000 RPM V8s). The regular Coyote in the Mustang and F150 were specrd 5W-20 (but recently bumped up to 5W-30), and they all have the same rod and crank bearing clearance specs. Of course these kind of cars use oil coolers to help control oil temps. Another example is older high RPM motorcycles that were simply air or water cooled with no active oil coolers, and they ran 10W-40 or 20W-50 all day long in track use at near redline and survived. The oil ran hotter with thicker oil but the bearings still survived because of more film thickness than a slightly cooler running thinner oil would provide.

 

[Oldwolf]

I've been running M1 FS 0W40 in my 2GRFE Sienna for a while now. Back in the day when I ran 0w20 I could get 27 to 28 miles per gallon while cruising on the highway. Now it seems I rarely get over 24. I'm thinking of a trying 0W-30 ESP next change and see if my MPG goes up.

 

[kschachn]

I've been running M1 FS 0W40 in my 2GRFE Sienna for a while now. Back in the day when I ran 0w20 I could get 27 to 28 miles per gallon while cruising on the highway. Now it seems I rarely get over 24. I'm thinking of a trying 0W-30 ESP next change and see if my MPG goes up.

You could try it but it’s unlikely to help much given the HT/HS of the ESP product. AFE would give a larger improvement although I don’t think there is any way you would tell the difference in everyday driving. The oil just doesn’t have that great a change on consumption compared to everything else.

If you’re really seeing up to a 4 MPG difference that’s something else other than the oil.