Can thicker oil cause more wear?

[sk_pete]

0w20 engines have "weaker" rings than lets say oldschool 15w40.
therefore in new car 0w20 it may do no damage, but in some old it can do harm. (metal-metal)
my engine spec 0w30/5w40 i chose latter.
imho, going far away from spec, up or down, can be harmful.

 

[kschachn]

0w20 engines have "weaker" rings than lets say oldschool 15w40.
therefore in new car 0w20 it may do no damage, but in some old it can do harm. (metal-metal)
my engine spec 0w30/5w40 i chose latter.
imho, going far away from spec, up or down, can be harmful.

Unless the winter rating is so inappropriate that it cannot be pumped, how can a higher grade be harmful? Where on that HT/HS chart does the plot curve upwards?

 

[sk_pete]

There's a point where that hydrodynamic friction can be come great enough to affect ring seal, hurting power and efficiency, and increasing oil transport past the rings leading to more oil consumption, coking, and carbon deposits in the top half of the engine.

i like this, because people step up grades if old engine has drinking problems, some are brave enough go from 5w30 to xw60
kschachn-maybe metal parts are fine with "too much" viscosity.
imho this SIZE]

 

[RDY4WAR]

It depends on what's facilitating the oil consumption in the cylinder. If the oil transport is due to a warped cylinder, then a more viscous oil could help the seal and slow the consumption. However, if the consumption is due to old, worn rings that have lost a good bit of tension (due to heat and wear), it could facilitate an increase in oil transport past the rings as that thicker oil film pushes the rings too far off the wall, effectively increasing clearance, and allowing intake vacuum to suck more oil past the rings on the intake stroke.

 

[930.engineering]

.
Hard to speculate about being harmful but there's little benefit beyond a certain point.
BMW allows for HTHS 3.0/0W-30 (LL-01 FE) and HTHS ~3.9/5W-40 (LL-01/LL-04) for my
Mini, while VW allows for HTHS 2.6/0W-20 (508 00) and HTHS ~3.9/5W-40 (502 00) for
my GTI. I'm fairly convinced beyond (or even before) that there's simply no gain in reducing
wear any further than that to be expected. The point is to avoid metal to metal contact and
ensure hydrodynamic lubrication. If moving parts are already separated they're separated.
What else would you want?
.

 

[ZeeOSix]

I don't get the straight lines above 2.6 cP that don't follow the data points.

You talking about the red line? That just shows in the data set that wear starts increasing at 2.6 cP and below for all RPM except at 2000 RPM.

 

[ZeeOSix]

I'm fairly convinced beyond (or even before) that there's simply no gain in reducing
wear any further than that to be expected. The point is to avoid metal to metal contact and
ensure hydrodynamic lubrication. If moving parts are already separated they're separated.
What else would you want?

I want some MOFT headroom ... not "just adequate enough" and operating at the ragged edge. I don't always want to think while driving around that I can't hammer my engine as much as I want because I'm on the ragged edge of MOFT and it could cause metal-to-metal wear if I push the engine too much.

 

[FZ1]

Dadgum boys! After reading all this thread and lookin' at all these, here, charts, I'm never takin' my 2017 Camry 2.5 over 3500 rpms.

 

[930.engineering]

I want some MOFT headroom ... not "just adequate enough" and operating at the ragged edge. I don't always want to think while driving around that I can't hammer my engine as much as I want because I'm on the ragged edge of MOFT and it could cause metal-to-metal wear if I push the engine too much.

Yes, agree, 'some MOFT headroom'. But no insanely excessive headroom.
Would you say a 10W-60 (HTHS ~5.8) would make any sense for me? I don't
think so, not even for my old Porsche. A reasonable headroom in this context
commonly means a manageable headroom of say 20 or 30 percent above the
recommendation which already incorporates a safety margin, say a headroom.
That's why I use 3.7 HTHS oil while VW says 2.6 is fine and BMW says 3.0 is ok.
Porsche used Shell TMO 10W-40 back in 1980. Oils vastly improved in recent
40 years. I don't have a clue what HTHS Shell TMO had but I'm certain enough
it wasn't 4.26 mPas/cP like what I run today.
So headroom is a good thing but first you need to define what you consider a
reasonable headroom. Remember higher viscosity equals to drag. Drag's not a
good thing.
.

 

[ZeeOSix]

Yes, agree, 'some MOFT headroom'. But no insanely excessive headroom.
Would you say a 10W-60 (HTHS ~5.8) would make any sense for me? I don't
think so, not even for my old Porsche. A reasonable headroom in this context
commonly means a manageable headroom of say 20 or 30 percent above the
recommendation which already incorporates a safety margin, say a headroom.
That's why I use 3.7 HTHS oil while VW says 2.6 is fine and BMW says 3.0 is ok.
Porsche used Shell TMO 10W-40 back in 1980. Oils vastly improved in recent
40 years. I don't have a clue what HTHS Shell TMO had but I'm certain enough
it wasn't 4.26 mPas/cP like what I run today.

I'd say you going from 2.6 HTHS to 3.7 is a big jump in headroom ... even more than what I do, lol. Welcome to the headroom club.

So headroom is a good thing but first you need to define what you consider a
reasonable headroom. Remember higher viscosity equals to drag. Drag's not a
good thing.

Based on engine wear vs oil viscosity studies, my definition of MOFT/HTHS headroom is something above 3.0 HTHS because many studies seem to agree that 2.6 HTHS and below is the point of increased wear due to minimal MOFT. A HTHS of 2.6 or below is on the ragged edge of adequate HTHS, especially if you push the engine. It might be fine and dandy for cruising around mellow at 2500 RPM all day, but not for me as that's not always my driving style.

 

[oilcandave]

Anyone who throws around technical terms like “0-20 wateroil” is obviously a highly trained and qualified expert in the field of tribology.

Some of ya must be a real blast to do an oil change with...

I don't participate in forums to let others know how much I know. I participate to learn and be entertained....and at times entertain..

There are a lot of smart people in the world but not too many pleasant folx..

 

[oilcandave]

Sounds like it snapped the wimpy distributor drive shaft, which was a pretty common failure if the engine was turned over in very cold weather with thick oil. I doubt it "wrecked the motor" though.

...just wiped off the gear drive off both cam and dist shaft. Brought it back to life..was a 1969 Toyota hilux and was lucky to find parts..

 

[Graham Piccinini]

Before anyone else replies to @oilcandave

 

[Accent Abuser]

I want some MOFT headroom ... not "just adequate enough" and operating at the ragged edge. I don't always want to think while driving around that I can't hammer my engine as much as I want because I'm on the ragged edge of MOFT and it could cause metal-to-metal wear if I push the engine too much.

I can definitely hear things getting very loud and gravely using a 20 grade above 5000rpm. My foot is always to the floor, tach banging off the redline and I frequently drive 90-100mph+ on the highway plus all my driving is at full operating temperature for very long stretches, in fact I drove all the way from New England down to Georgia (1200 miles) over the holidays like a bat out of hell and had no problems or disconcerting noises using Castrol Edge 10w-40. Must be working for me because I've been driving it like that for over 171k with absolutely zero engine problems or consumption issues.

Even my fuel economy is largely unphased by a higher viscosity, it's mostly dependant on my speed or traffic. Just today I got 41.5mpg going a steady 55mph on Highway 280 using Mobil 1 FS 5w40.

If you drive like a grandma or do mostly short trips go right ahead and use a 20 grade, I don't think it's a "water oil", I just don't think it's appropriate for my driving style, especially in a Hyundai engine.

 

[aquariuscsm]

Castrol Edge 10w-40.

Are you using the older formula Edge 10W-40?

 

[930.engineering]

Even my fuel economy is largely unphased by a higher viscosity, it's mostly dependant on my speed or traffic.

That's out of question. Where did you ever see anyone claiming something else?
.

 

[930.engineering]

I'd say you going from 2.6 HTHS to 3.7 is a big jump in headroom ... even more than what I do, lol. Welcome to the headroom club.

I even doubt the factory fill back in 2017 was actually 0W-20 / VW 508 00.
Guess it's been VW 504 00 and likely SHUP AV-L 0W-30 (Pennzoil Euro LX).
If that's true (and if it even matters) that's just a small step from 3.5 to 3.7
mPas/cP in HTHS. Enough for me given the engine seems fine even with 2.6.
.

 

[Accent Abuser]

Are you using the older formula Edge 10W-40?

The SP version.

 

[Silver]

Not a typical scenario, but I've seen this happen more than once before.

Drag racing engines, particularly OEM blocks with unmodified oil passages, using stock/low oil capacity with a high volume oil pump and a viscous oil like 20w-50 with oil temp that's just 120°F because it's not running long enough to heat up.

On the top end of the track, at high rpm, the driver notices the oil pressure has gone from 70 psi to 0 psi. The breathers in the valve covers are soaked in oil. Two seconds after letting off the throttle, the oil pressure goes back to near 70 psi. The oil pump is cavitating because it's pumping more volume than the viscous (100+ cSt at that temp) oil can drain back to the pan. All of the stock sump's capacity is in the heads and lifter valley.

Related to that, I've seen quite a few snapped oil pump drives in older Ford small blocks using a viscous 15w-40 to 20w-50 oil in cold temperatures. Usually the idiot owner/user cranking it up at

This is just one example of the somewhat illegitimate claim that oil flows like it's in a single pipe throughout the engine, ignoring the fact that some oil flow is dictated by gravity (or something other than a simple direct connection to the pump), where a less viscous oil would benefit during startup conditions where "x amount of engine wear occurs" so they say.