All You Guys That Think OEM Recommended 16 or 20 Weight...

[loneryder]

That statement has a small amount of truth to it that's a bit exaggerated. You won't have issues from the start. Some VVT/VCT engines that use oil pressure for activation may be sensitive to it at operating temp, but not likely cause damage of any sorts.

The issue from this would be a very niche concern. Let's take NASCAR engines for example. They have extremely precise machining (Bryant crankshafts are marvels of precise engineering) with very tight clearances
Aside from the bearings, the hydrodynamic friction from higher viscosity can be a major power killer. It can have a huge effect, into double digit horsepower losses, with higher viscosity when the piston speeds are exceeding 75 fps.

You are saying that Nascar race cars use 0-16 and 0-20???

 

[tolian21]

You are saying that Nascar race cars use 0-16 and 0-20???

They buy oil at walmart

 

[OVERKILL]

I wonder how many modern engines have spray nozzles to make sure the bores get enough oil. They used to be rare, but quite common now.

Are you thinking of piston cooling jets? Because the primary purpose isn't bore lubrication but rather cooling the bottoms of the pistons in high performance applications.

 

[OVERKILL]

You are saying that Nascar race cars use 0-16 and 0-20???

I'm of the impression that they most definitely use very thin oils for qualifying but, depending on the event, may use a heavier oil (I'm sure the grade varies) depending on the length of the event and the track itself.

 

[tolian21]

Most NASCAR engines are designed to last 500 miles and/or one race. They are typically rebuilt at that point. They will be happy with any oil that provides max horse power and keeps engine working before its time for next rebuild.

 

[Jetronic]

Are you thinking of piston cooling jets? Because the primary purpose isn't bore lubrication but rather cooling the bottoms of the pistons in high performance applications.

Yes, but I've seen seized diesel engines when the nozzles weren't working. Seizing can be due to heat expansion or lack of lubrication of course. I don't think you can seperate either, the oil hits both the bore and the underside of the pistons.

 

[OVERKILL]

Yes, but I've seen seized diesel engines when the nozzles weren't working. Seizing can be due to heat expansion or lack of lubrication of course. I don't think you can seperate either, the oil hits both the bore and the underside of the pistons.

Yes, I've just not observed a longevity difference with/without them in gas engines. Their most common use is in performance builds (my 6.4L has them).

 

[ZeeOSix]

Hey, don't argue with me. I'm simply quoting from an article in enginebuildingmag.com.

They might want to change the name of the magazine.

 

[ZeeOSix]

"Contributing factors that can cause oil pressure and lubrication problems in an engine include:

5. Bearing clearances too tight for the oil viscosity being used. Late model engines such as a Chevy LS or Ford modular V8 with tighter main and rod bearing clearances of .0015˝ to .002˝ usually require a thin multi-viscosity motor oil such as 5W-20. Fill the crankcase with a relatively thick racing oil and you’ll have problems right from the start. Tighter bearing clearances require thinner oils..." https://www.enginebuildermag.com/2017/03/engine-bearing-technology-spin-spun-bearings/

Ford Coyote V8s have bearings specs tight ... yet Ford put 5W-50 in them. Also Corvette engines run clearances that tight, and they spec xx-40. Go figure.

 

[ammolab]

Ford Coyote V8s have bearings specs tight ... yet Ford put 5W-50 in them. Also Corvette engines run clearances that tight, and they spec xx-40. Go figure.

My Chevy SS has an LS engine…an LS3 used in many Corvettes and Camaros also. Required oil is 5W-30

 

[ZeeOSix]

Bearings spin when there's not enough separation...

AKA ... enough metal to metal contact due to MOFT going to zero to weld the journal to the bearing which makes the bearing spin around.

 

[Astro14]

Wow….

Those “modern” engines have the same bearing clearance specifications as the 1932 Packard.

Not that tight, in other words.

All of that “designed for thinner oils” and “modern manufacturing” talk appears to be just talk.

The proper viscosity for a given application has far more to do with operating conditions, including temperature, than engine clearances and manufacturing tolerances.

 

[ZeeOSix]

A nugget of truth is the rod and crank spillage have to lube and cool the cylinder bores.
So there is a bit of truth to volume flow. Not a bearing lube issue.
And don't give me that "positive displacement oil pump" balogna.
If the oil pump has an exit ramp berfore the mains drill- that's where the "extra" oil is flowing.

No correctly designed engine oiling system is going to starve bearings when the oil is at operating temperature and the pump is in pressure relief. Why do you think the pressure relief is set to a high value? The difference in flow at pressure relief between xW-16 and xW-50 at operating temperature isn't going to matter. If it did, all those Boss 302 Mustangs running 5W-50 would have blown-up on the tracks all across America. And besides, a PD pump is going to be more efficient with a thicker oil due to less rotor slippage (ie, less oil leakage at the rotor tips).

 

[ZeeOSix]

The issue from this would be a very niche concern. Let's take NASCAR engines for example. They have extremely precise machining (Bryant crankshafts are marvels of precise engineering) with very tight clearances

What kind of oil pressure and pump volume is going on at 8000 RPM? Keep in mind that at 8000 RPM the journal bearings are more centered than if they were running at a much slower speed. Higher RPM helps increase the MOFT inside journal bearings. I'd like to see a set of bearings after a race, I'm betting they are not pristine.

 

[ZeeOSix]

They buy oil at walmart

I'd like to see the formulation of those NASCAR oils. Probably packed with AW additives so the parts don't weld together when MOFT goes to zero.

 

[DirectRejection]

Most NASCAR engines are designed to last 500 miles and/or one race. They are typically rebuilt at that point. They will be happy with any oil that provides max horse power and keeps engine working before its time for next rebuild.

And as for NHRA ??

 

[xgmad]

my dad run 20w50 in a 2020 camry, is it dead yet? no
clearances are not too tight to not let thick oil in.
These thin oils are for fuel economy.

Do any of you remember when ford began specifying 5w20 in their f150's and they started dying due to increased stress and the oil not being able to handle it due to old oil system? 5w20 has gone a long way though since 2001.

 

[RDY4WAR]

Most NASCAR engines are designed to last 500 miles and/or one race. They are typically rebuilt at that point. They will be happy with any oil that provides max horse power and keeps engine working before its time for next rebuild.

So long as the engine is in good health, they'll go 3-4 races before a rebuild. (1,500-2,000 miles) A lot of times, the engine doesn't "need" a rebuild at that point. It just may be down a few hp compared to new. The exception would be if they qualify poorly or have an issue with tech, they'll put a fresh engine in since they have to start at the back of the pack anyway.

 

[ka9mnx]

Are you thinking of piston cooling jets? Because the primary purpose isn't bore lubrication but rather cooling the tops of the pistons in high performance applications.

Corrected it for you.

 

[ka9mnx]

I'm of the impression that they most definitely use very thin oils for qualifying but, depending on the event, may use a heavier oil (I'm sure the grade varies) depending on the length of the event and the track itself.

Correct me if I'm wrong but about 15 years ago, NASCAR at least, made a rule change that after qualifying the engine couldn't be touched before the race. Engine oil couldn't be changed.