HTHS question (high vs. low)

[Curious Kid]

Originally Posted By: AEHaas
We need to stop clinging to older, outdated information. We need to move ahead and accept progress. It is human nature to hang on to older yet inferior things. We cannot help it.


When evidence clearly dictates for the individual, and circumstances call previous behaviors into question/arouse doubt...change may very well ensue. There's a degree of investment that shares weight, especially when one sees a vehicle as a poor yet essential investment for enabling a less dependent livelihood - though that might prove a falsehood/sign of ignorance.?.

I'm not against lighter weight oil's, in fact I'm running a mix of SM 5w30 and 0w-20 in a vehicle that spec's 5w30 as the lowest winter weight in SH variety. The vehicle sees mostly short trip use and the oil doesn't see full temp often/for long, so I feel confident and enjoy the decreased valve clatter due to thinner oil viscosity at cold start due to some failing o-rings in the modular engine's pick-up circuit which I will replace this spring/summer.

Take care.

 

[d00df00d]

So, where a thin oil protects as well as a thick one, it has to be down to the barrier film, right? I take it that going to a thinner oil is essentially giving up on hydrodynamic lubrication in high stress regions in the engine. I imagine that wouldn't be too hard a choice to make in a racing application where the sustained high loads and RPM will squeeze, spin, and shear oil out of bearings very quickly...

Again, please correct me if I'm wrong, or fill me in if I'm missing something!

 

[TallPaul]

Originally Posted By: d00df00d
What I heard was in the context of using something like Fuchs Titan GT1 0w-20 in an app that specced a 30wt or 40wt. I can't imagine that wouldn't produce a significant MPG gain, given that some people have measured MPG differences between GC and a thinner 30wt...
I guess significance is in the eye of the beholder. Perhaps statistically significant, though it's tough to get good data unless you live in a static climate and each trial needs many tankfulls to minimize variances like how full the tank gets each time and variations in other conditions (weather, trip length, etc.). Then if the fuel consumption improvement is statistically shown to be significant, say at the alpha=0.05 level, then are the cost savings significant in terms of your total budget/cash flow situation. Will the cost of Fuchs over say Maxlife make up for the fuel cost savings?

Sorry about the cavalier nature of my earlier post.

 

[AEHaas]

Many "sports car" engines are ruined within a few thousand miles and again the oil is blamed. The most common cause is cavitation. Hugh chunks of bearing material can be removed by this process. Only this type of bearing damage can be deep or a full thickness loss.

I see this often, somebody gets in the car, starts it up and revs it right up to redline. The oil is thick as mud and cavitation takes its toll. This is one of the major reasons I use thinner oils. It is why I look first at the 40 C viscosity. I want to be able to step on it early, if needed, and not worry about cavitation. There will still be the usual wear until the oil warms up to operating temperature but at least I minimize cavitation.

This is my thinking. Why nobody ever discusses this is something I do not understand. RLI motor oils are the most fluid at room temperature and this is why I am using them next.

aehaas

 

[azsynthetic]

Originally Posted By: AEHaas

I see this often, somebody gets in the car, starts it up and revs it right up to redline. The oil is thick as mud and cavitation takes its toll. This is one of the major reasons I use thinner oils. It is why I look first at the 40 C viscosity. I want to be able to step on it early, if needed, and not worry about cavitation. There will still be the usual wear until the oil warms up to operating temperature but at least I minimize cavitation.

aehaas


If your engine has oil cavitation problem then it is a deficiency in engine design and/or specification. There is no oil that will prevent operator stupidity.

 

[Doug Hillary]

Hi,
aehaas - surely IMHO the following Post needs a greater definition and some enlightenment as to the better characteristics of RLI at room temperature (surely you mean at ambient?):

Poster: AEHaas
Subject: Re: HTHS question (high vs. low)

Many "sports car" engines are ruined within a few thousand miles and again the oil is blamed. The most common cause is cavitation. Hugh chunks of bearing material can be removed by this process. Only this type of bearing damage can be deep or a full thickness loss.

I see this often, somebody gets in the car, starts it up and revs it right up to redline. The oil is thick as mud and cavitation takes its toll. This is one of the major reasons I use thinner oils. It is why I look first at the 40 C viscosity. I want to be able to step on it early, if needed, and not worry about cavitation. There will still be the usual wear until the oil warms up to operating temperature but at least I minimize cavitation.

This is my thinking. Why nobody ever discusses this is something I do not understand. RLI motor oils are the most fluid at room temperature and this is why I am using them next.

aehaas

I have rarely seen "cavitatiuon" as a cause of engine failure. I have seen lubricants that do NOT have a suitable HTHS viscosity cause excessive component wear. Some of this will NOT be picked up by UOA and is only able to be suitably analysed at engine tear down

IMO only those engine lubricants as specified by the engine manufacturer are suitable for GENERAL use

Regards

 

[d00df00d]

Originally Posted By: azsynthetic
If your engine has oil cavitation problem then it is a deficiency in engine design and/or specification. There is no oil that will prevent operator stupidity.

I agree with the second assertion, but I think the first needs work...

 

[d00df00d]

Originally Posted By: Doug Hillary
I have seen lubricants that do NOT have a suitable HTHS viscosity cause excessive component wear. Some of this will NOT be picked up by UOA and is only able to be suitably analysed at engine tear down

How is that? Not at all suggesting you're wrong, just curious.

 

[azsynthetic]

Originally Posted By: d00df00d
Originally Posted By: azsynthetic
If your engine has oil cavitation problem then it is a deficiency in engine design and/or specification. There is no oil that will prevent operator stupidity.

I agree with the second assertion, but I think the first needs work...


Please clarify what part of the first sentence you need help with. If there is a cavitation problem then either the engine lubrication system is defective in either design/production or the usage specification is incorrect. Oil alone will not cure cavitation issues nor operator stupidity, I wish it would.

 

[Doug Hillary]

Hi,
d00df00d - wear on some engine components will not neccessarily show up in a simple UOA. An "in depth" UOA including PQ Index results and etc. do aid in analysing the results but will not pick up certain component deterioration
Some forms of corrosion "wear" pitting of camshafts is but one example!

Cam components are but one example where a suitable HTHS viscosity is critical - closely followed by turbochargers and other actuators etc

If your engine manufacturer calls for a lubricant with a HTHS vis. of say 3.5cSt it is simply a sensible decision to use one. Ask any user of a diesel engine from CAT, Cummins, Detroit or any such engine from a European maker!

Regards
Doug

 

[bruce381]

""RLI motor oils are the most fluid at room temperature and this is why I am using them next."'

Since the published specs seem a all over compared to what comes in a bottle have you done a VOA yet?

bruce

 

[lewk]

I think what aehaas meant in his post was thinner oils at the early cycle of an engine start will provide better flow in case the driver decides to "get in it", not that the oil created the cavitation problem it just was not "ready" to prevent it.

 

[Doug Hillary]

Hi,
lewk - As you are well aware most of us know that. That is why for "general" use the manufacturer's lubricant recommendations are so important

Still, engines that are started up cold and quickly taken to higher revs do not seem to figure in Warranty claims issues!

I am very aware of "Techs" and others who know best with lubricants and this is a serious matter! VW and MB in NA know a lot about that and so do many heavy diesel engine manufacturers

For instance in Sydney Australia we have a Porsche repair shop recommending and installing a 25w-50 (mineral of course) lubricant in 928 V8s. The factory fill in this particular engine family was 5w-40 synthetic!! It is possible to have -10C in Sydney and much lower temperatures elswhere here

Porsche have NEVER recommended using a 25w-50 lubricant EVER!

The trend is certainly towards a freeflowing cold start lubricant and even in heavy diesel engines

Regards

 

[d00df00d]

Originally Posted By: TallPaul
I guess significance is in the eye of the beholder. Perhaps statistically significant, though it's tough to get good data unless you live in a static climate and each trial needs many tankfulls to minimize variances like how full the tank gets each time and variations in other conditions (weather, trip length, etc.). Then if the fuel consumption improvement is statistically shown to be significant, say at the alpha=0.05 level, then are the cost savings significant in terms of your total budget/cash flow situation. Will the cost of Fuchs over say Maxlife make up for the fuel cost savings?

Sorry about the cavalier nature of my earlier post.

No sweat.

I see what you're saying, and I agree.

I also agree with Doug here:
Originally Posted By: Doug Hillary
If your engine manufacturer calls for a lubricant with a HTHS vis. of say 3.5cSt it is simply a sensible decision to use one.

My car's manufacturer actually does call for a HTHS value of at least 3.5. Given that my car seems barely able to maintain proper pressure at idle with a thick 30wt in stop-and-go traffic on the hottest days here, I don't think I'll be testing 20wt oils any time soon.

My interest in this matter is mostly academic, to be honest. I'm fascinated by the idea of an easily pumpable fluid that is able to protect under the most stressful conditions.

Speaking of which, thanks for the ongoing discussion, everyone!

 

[Curious Kid]

The manual on my vehicle says nothing of the like concerning HTHS, just a lower cap of 5w30 for extreme cold/cool weather to 15w40 for extreme heat and sustained mountainous driving/tow loads in a API SG/SH variety. Oh well. For better or worse...it's just a nagging source of what I deem insufficient information/specification to this yet "enlightened"/still neurotic individual concerning machine design and maintenance.

I guess the engine controls me!

Take care, and great discussion!

 

[Pablo]

Originally Posted By: Curious Kid
The manual on my vehicle says nothing of the like concerning HTHS...


In a way they are. Please look at this:

http://www.infineum.com/information/api-viscosity-2004.html

You will note the oil viscosities given have a lower HTHS limit.

Doug Hillary is spot on, I’ll just add that in a street engine even in extreme conditions there is no short or long term benefit of having an oil that greatly exceeds engine design controlled HTHS requirements.

 

[Curious Kid]

I see what you are saying, but then there's some sense of economy influence AND from the literature on the 850's intro in '93, it was mentioned the engine had a 200,000 mile life expectancy. I suppose that is by following the manual to a "T", but under what operating environment - German motoring or grocery getting???

I guess it's my nature to try in vain!

Take care.