Can thicker oil cause damage?

[OVERKILL]

Originally Posted By: zjones
Thank you OVERK1ll Edited for clarity


No problem. I edited my post as well, to cite a couple examples.

 

[river_rat]

Originally Posted By: vxcalais
Redlines HTHS 5w20 is higher or equal to the next grade up...

Good point.
I'm looking at a couple SAE papers here that says there is little correlation between kinematic viscosity and bearing wear, but there is between HTHS and bearing wear. I tend to look at HTHS over viscosity as long as the oil pressure holds up. The anti-wear add pack more than HTHS seems to be mostly responsible for preventing cam/lifter or timing chain wear.
There seems to be no wear prevention advantage when the HTHS exceeds about 3.5.

Having said that, the thicker oils certainly do tend to have higher HTHS - all other things being equal.
Now, in my air-cooled VW engine, which has faily large oil clearances and a lot of heat expansion, I always run 20W-50 except in the winter.
That gives me about 10-11 psi / 1000 RPM at full temperature, and I feel like any less than that, I risk oil not having enough pressure to make it to #1 main bearing (thrust) in the volume it needs.

 

[Garak]

Originally Posted By: zjones
Might want to heed mfg engineer's advice in this area. I personally cannot think of one single benefit running thicker viscosity oil outside mfg specs for it's normal service life


What about when a manufacturer specs, say, a 5w-20 for the vehicle in North America, but, say, a Xw-40 in Europe for the exact same engine. Either the engineers have gone nuts or it's not as big a deal as some make it out to be.

 

[OVERKILL]

Originally Posted By: Garak
Originally Posted By: zjones
Might want to heed mfg engineer's advice in this area. I personally cannot think of one single benefit running thicker viscosity oil outside mfg specs for it's normal service life


What about when a manufacturer specs, say, a 5w-20 for the vehicle in North America, but, say, a Xw-40 in Europe for the exact same engine. Either the engineers have gone nuts or it's not as big a deal as some make it out to be.


My favourite example of that is the Ford Modular actually.

The engine in the Mustang GT specs 5w20. The engine in the GT500 specs 5w50. With the SAME clearances.

 

[simple_gifts]

Originally Posted By: Panzerman
Well, I ve had no problems anytime I tried a thicker oil, but I have read alot of Hypotheticals on here from your starter wont be able to turn the engine over and your engine will knock for the first 15 minutes of start-up till the oil gets warm enough to move. Mostly propaganda put out by manual followers, too skeered to try the thick stuff.


How come all the cold oil experts live in Florida? (j/k)

As a side point, my old cast iron I6 sounded quite "raw" at 0F, with a myriad of noises not found @ full temp, but this is probably related to cold, not thick oil. (or is that the same)

 

[zjones]

Originally Posted By: Garak
Originally Posted By: zjones
Might want to heed mfg engineer's advice in this area. I personally cannot think of one single benefit running thicker viscosity oil outside mfg specs for it's normal service life


What about when a manufacturer specs, say, a 5w-20 for the vehicle in North America, but, say, a Xw-40 in Europe for the exact same engine. Either the engineers have gone nuts or it's not as big a deal as some make it out to be.


I can't be sure...However for example we know European Standards are considerably different from USA Standard regarding oils...Castrol Edge for example...different oil between the States and Europe but they call it the same stuff.

 

[Garak]

Originally Posted By: zjones
I can't be sure...However for example we know European Standards are considerably different from USA Standard regarding oils...Castrol Edge for example...different oil between the States and Europe but they call it the same stuff.


Hmmm, that really depends. Is a European 5w-40 far superior, whatever that means, to a North American 5w-40? I don't think my Delvac 1 5w-40 is inferior to few, if any oils, at least for my application. Certainly there are different oils between the two continents. GC is different than regular Syntec, for sure. Much of the difference is the way they define synthetic in Europe and how they define it here. Castrol opened that can of worms themselves.

So, by that logic, it should be okay for a person using a 5w-20 in North America to switch to GC (which is a very heavy 30 weight) without problems, because it's a European spec oil, right? Or, we could all have our oil changed at BMW, Benz, and Audi dealerships for the "superior" oil with proprietary European specifications?

I don't buy into the argument. I have no doubt that 5w-20 is a good grade and perfectly adequate for most engines that require it. It's no coincidence, however, that CAFE affects only vehicles sold in the United States (and Canada, by proxy). 5w-20 is more valuable to the manufacturers' bottom lines than it is to the consumers.

If I had a vehicle calling for 5w-20, I'd be inclined to go to a 0w-20 in the winter. -40 is unpleasant, and common enough here. For towing, switching to a heavier oil may be of benefit.

I'm just not convinced of the "one oil for all applications and all circumstances" position.

 

[mechanicx]

If I had to guess the only place a thicker oil would cause more wear is during cold start in the rings and cylinder walls that get mostly splash lube. I'm not sure how much of a factor it would be since cold start cylinder wall wear is mostly due to cold parts and clearances. This is mostly a factor in cold temps of winter and with a 0W40 or 5W40 how much difference would a 0w20 or 5W20 make?

 

[Garak]

Originally Posted By: mechanicx
This is mostly a factor in cold temps of winter and with a 0W40 or 5W40 how much difference would a 0w20 or 5W20 make?


Quite right. When it gets down to -40, the first number is certainly more important. In any case, none of them are going to flow wonderfully right off the bat, unless you use an oil pan heater. If someone is that concerned about cold starts, that's about the only option up here.

 

[Gary Allan]

Quote:
I don't buy into the argument. I have no doubt that 5w-20 is a good grade and perfectly adequate for most engines that require it. It's no coincidence, however, that CAFE affects only vehicles sold in the United States (and Canada, by proxy). 5w-20 is more valuable to the manufacturers' bottom lines than it is to the consumers.


I can't buy into it either. All oils transition through the same visc at different times. A 5w-20 forced cooled to 160F will be a 40 grade. The acceptable variance in peak (normal - steady state) oil temps depending on the variable (load, etc.) will span a full grade PLUS.

I tend to take the inverted view on the CAFE reference. It's obvious that engines survive just fine in either environment on either diet of higher vs. lower visc. Physics just doesn't take a vacation at the 200 mile limit. Everyone looks at visc in isolation and anoint it with magical properties.

 

[SpitfireS]

There is at least one post on an S2000 forum about a German owner using Castrol Racing 10W-60 in an S2000 (F20C2 engine) ending up with a scored #4 cylinder wall due to "oil starvation" at sustained high rpm (>8000)
The F20's are IMO designed around a 30 weight.

 

[sangyup81]

Originally Posted By: fdcg27
I have been using thicker than spec oils in some of our cars for the past few years.
The van was the first victim, having seen QS syn 5W-50 and Syntec 5W-50, as well as M1 EP 15W-50, a blend of 2 qts GTX 20W-50 + 3 qts GTX 5W-20, a well as Tection Extra 15W-40.
The Havoline DS 10W-40 in it currently is probably too close to spec to count.
The '97 Accord was on Tection 15W-40 for one run last summer, and is now on M1 EP 15W-50. It has seen PYB 10W-40.
The '99 Accord is now on the same M1 EP 15W-50 it saw last summer. It has also seen PYB 10W-40.
I have never noted any ill effects with the thicker oil, which I only use during warm weather. There doesn't seem to be much loss of fuel economy, either.
Has anyone seen any actual damage caused by the use of thicker than spec oil in warm weather?


I'm curious how 5w50 and 0w50 do in the winter. Theoretically they should flow better than typical 10w30s and hopefully the 0w50 flows better than a 5w20? That might be stretching it though

 

[aquariuscsm]

Originally Posted By: sangyup81
Originally Posted By: fdcg27
I have been using thicker than spec oils in some of our cars for the past few years.
The van was the first victim, having seen QS syn 5W-50 and Syntec 5W-50, as well as M1 EP 15W-50, a blend of 2 qts GTX 20W-50 + 3 qts GTX 5W-20, a well as Tection Extra 15W-40.
The Havoline DS 10W-40 in it currently is probably too close to spec to count.
The '97 Accord was on Tection 15W-40 for one run last summer, and is now on M1 EP 15W-50. It has seen PYB 10W-40.
The '99 Accord is now on the same M1 EP 15W-50 it saw last summer. It has also seen PYB 10W-40.
I have never noted any ill effects with the thicker oil, which I only use during warm weather. There doesn't seem to be much loss of fuel economy, either.
Has anyone seen any actual damage caused by the use of thicker than spec oil in warm weather?


I'm curious how 5w50 and 0w50 do in the winter. Theoretically they should flow better than typical 10w30s and hopefully the 0w50 flows better than a 5w20? That might be stretching it though


I`ve always wondered if a 5W50 will have as good or thick of an oil film as a 20W50 once good and hot,say,at the engine`s hottest operating temperature.

 

[Gary Allan]

Quote:
I'm curious how 5w50 and 0w50 do in the winter. Theoretically they should flow better than typical 10w30s and hopefully the 0w50 flows better than a 5w20? That might be stretching it though


They will pumpable at a lower temp. I don't think I would morph that to mean flow "better".

 

[fdcg27]

Originally Posted By: Gary Allan
Quote:
I don't buy into the argument. I have no doubt that 5w-20 is a good grade and perfectly adequate for most engines that require it. It's no coincidence, however, that CAFE affects only vehicles sold in the United States (and Canada, by proxy). 5w-20 is more valuable to the manufacturers' bottom lines than it is to the consumers.


I can't buy into it either. All oils transition through the same visc at different times. A 5w-20 forced cooled to 160F will be a 40 grade. The acceptable variance in peak (normal - steady state) oil temps depending on the variable (load, etc.) will span a full grade PLUS.

I tend to take the inverted view on the CAFE reference. It's obvious that engines survive just fine in either environment on either diet of higher vs. lower visc. Physics just doesn't take a vacation at the 200 mile limit. Everyone looks at visc in isolation and anoint it with magical properties.


I decided that the 15W-50 would cause no harm largely based upon your previously having noted this multiple times.
All oils share the same viscosity at different tempearatures.
If the 15W-50 is too thick on a fifty degree morning, then the 0W-30 I used over the winter was also too thick on a ten degree morning.
I tried to avoid looking at visc in isolation.
An important factor in my thinking wrt the 15W-50 is the way in which the cars are used.
Both are started and driven a considerable distance each morning and each afternoon.

 

[mechanicx]

Originally Posted By: SpitfireS
There is at least one post on an S2000 forum about a German owner using Castrol Racing 10W-60 in an S2000 (F20C2 engine) ending up with a scored #4 cylinder wall due to "oil starvation" at sustained high rpm (>8000)
The F20's are IMO designed around a 30 weight.

This is where I was saying a thick oil may be a problem at the cyliner walls, pistons and and rings. I was thinking more at the other extreme of cold engine operation and during warm up causing higher wear. I never really thought of it at the other extreme, high RPM at sustained RPM. Did this guy allow the oil to get up to operating temperature before ripping on the engine, or was it truely sustained hot running and still got oil starvation at the cylinder walls at extreme RPM and load?

 

[mechanicx]

Originally Posted By: fdcg27


I decided that the 15W-50 would cause no harm largely based upon your previously having noted this multiple times.
All oils share the same viscosity at different tempearatures.
If the 15W-50 is too thick on a fifty degree morning, then the 0W-30 I used over the winter was also too thick on a ten degree morning.


Right they were both too thick and is probably part of the reason you see much higher wear during warm up engine operation. It's only for a short period of time till the oil warms up, but why not start as thin as you can and still have adequate hot viscoity?

 

[2oldtommy]

There is a blizzard of oil movment in an engine at >8K RPM. The comment that #4 piston failed due to "oil starvation" is certainly incomplete. Had all the cylinder walls been scored, then we might accept this analysis. Something else is going on here.( Broken ring, pre ignition) FWIW--Oldtommy

 

[AEHaas]

"It's only for a short period of time till the oil warms up"

This should be clarified. Your coolant may only take a few minutes to warm up to the normal operating temperature but your oil will take up to 30 minutes to get up to say 200 F. It will be somewhat faster if you start and go immediately into WOT, wide open throttle.

aehaas

 

[badnews]

Originally Posted By: river_rat
Originally Posted By: vxcalais
Redlines HTHS 5w20 is higher or equal to the next grade up...

Good point.
I'm looking at a couple SAE papers here that says there is little correlation between kinematic viscosity and bearing wear, but there is between HTHS and bearing wear. I tend to look at HTHS over viscosity as long as the oil pressure holds up. The anti-wear add pack more than HTHS seems to be mostly responsible for preventing cam/lifter or timing chain wear.
There seems to be no wear prevention advantage when the HTHS exceeds about 3.5.

Having said that, the thicker oils certainly do tend to have higher HTHS - all other things being equal.
Now, in my air-cooled VW engine, which has faily large oil clearances and a lot of heat expansion, I always run 20W-50 except in the winter.
That gives me about 10-11 psi / 1000 RPM at full temperature, and I feel like any less than that, I risk oil not having enough pressure to make it to #1 main bearing (thrust) in the volume it needs.



Best answer posted as yet IMO