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Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity

Callisa

HTHS is a means of comparing oils of same viscosity when in the performance area, greater film strength at same oil temp, or dropping viscosity giving greater flow but maintaing film strength.
Porsche specify 3.6 or above.

As far as I know
MoS2 is a suspended, non-soluble micro-powder. As such it can settle out in storage when used as an additive in motor oil. However, MoDTC is a fully oil soluble salt, will not settle out in storage, and, in solution, passes freely through the oil filter. (Since it's in solution, it can't "clump".) However, heat and pressure (of which there's plenty inside an operating engine at points of sliding metal-to-metal "contact") will allow the molybdenum to be deposited and "fused" with those sliding metal surfaces as an anti-wear, last-line-of-defense, extreme pressure agent micro-coating in the event the oil film is briefly disrupted.
To understand the situation today, you have to understand what happened in the past. Early XW-30 formulations where by far not as capable concerning wear protection as they are today. It is believed and commonly accepted by mechanical engineers (not by Lube Engineers...) that the conrod bearings of high RPM engines need high viscosity / HTHS oils to survive.
But "lessons learned" from the past with these early formulations are still very deep in the heads of the engineers at Porsche, Alfa, Ferrari etc.
Mechanical Engineers are a conservative, tough crowd... Roll Eyes
Callisa,

Going back in history, if you take a classic mini then a 20W50 was specified, but then it did chew improvers.
With more wear on start up perhaps with more stable oils 10W40 appeared to be standard recommendation and now M1 0W40 with HTHS of 3.6.

If a minimum HTHS of 2.6 is required to prevent excessive wear, this may only be ok if not using car after warranty period.

Honda may therefore specify a 0W20 for a high rev engine, however BMW found a problem with some engines and specified a xW60.

Somewhere inbetween may be a good compromise but we are limited by the Mechanical Engineers view of wear in the whole engine and protecting the weak spots.

Without guidance there appears to be a risk to move away from the manual for any particular engine.

Therefore can reducing viscosity and improving flow and temperature control make up for the higher protection provided by a higher viscosity and HTHS, and is it worth taking that risk and dropping viscosity?

The comparison is that WRC use a 5W40 but F1 use a straight 5 or 10.
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however BMW found a problem with some engines and specified a xW60.

True. They found a problem with the engine and fixed the engine hardware problem with oil!

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Without guidance there appears to be a risk to move away from the manual for any particular engine.


True. I wrote that in the past more than once.

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higher protection provided by a higher viscosity and HTHS

Let's say you are 1 meter away from an edge. Behind the edge is the Grand Canyon, and you may fall down and hurt yourself.
Are you now safer by staying two meters awy from the edge instead of one meter?
I don't think so. Wink
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Originally posted by Callisa:
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higher protection provided by a higher viscosity and HTHS

Let's say you are 1 meter away from an edge. Behind the edge is the Grand Canyon, and you may fall down and hurt yourself.
Are you now safer by staying two meters awy from the edge instead of one meter?
I don't think so. Wink
I prefer 2 meters as it exceeds my height a bit. Therefore if I fall, I fall entirely on solid ground, not 40% over the abyss, which very well might propell me over the edge. Eek
Callisa,

My assumption is that the oil engineer will spec the oil according to the weakest link within engine and current oil specification.

However its also possible that the car could be used for short shopping trips or an owner that lets the horses loose.

The oil engineer I assume takes this into account.

With Porsche the latter owner is more likely and perhaps therefore the 3.6 HTHS recommendation. Wheras the former driver may require improved mpg so a thinner oil is specified.

So the Porsche owner may actually want to stand on the edge a little more often.

The paradox is that by using a thinner oil with more flow and better cooling, you may be able to stand on edge anyway.

My problem is the manual was written 30 years ago and specified a 20W/50 Mineral oil.
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Originally posted by Callisa:
Well, what can one expect if someone stores oil for the next 3 years in his cellar... Big Grin
My stash has dropped below 100 quarts. There is a sale on Valvoline at Pep Boys. Guess I'm going to buy some more oil today. Hopefully there is still some SL on the shelves. None of that watered down SM stuff for me! Big Grin
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My stash has dropped below 100 quarts. There is a sale on Valvoline at Pep Boys. Guess I'm going to buy some more oil today. Hopefully there is still some SL on the shelves. None of that watered down SM stuff for me!


Stay with ACEA A3/B3/B4 2002 oil qualities if you don't want to switch to API SM. I made some time ago a comparison in terms of testing limits allowed between ACEA and API SL. You will get for sure a better oil quality with ACEA. Wink
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My assumption is that the oil engineer will spec the oil according to the weakest link within engine and current oil specification.

He Specs the oil according to the service interval requirements and weakest point of the engine, than designs his oil specification. The mineral oil guys will do an oil development if they see a business case for such an oil quality.

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However its also possible that the car could be used for short shopping trips or an owner that lets the horses loose.

Short trip cycle is worst case. The oil has to be changed anyway no matter what quality is used. An owner that lets the horses loose is best case for gasoline engines. He will accumulate miles within a short time and has to go to an oil change after a fixed limit. (e.g Germany for many OEM's: 30.000 km)

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Wheras the former driver may require improved mpg so a thinner oil is specified.
Yes.
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Originally posted by Callisa:
Stay with ACEA A3/B3/B4 2002 oil qualities if you don't want to switch to API SM. I made some time ago a comparison in terms of testing limits allowed between ACEA and API SL. You will get for sure a better oil quality with ACEA. Wink
Thanks for the advice. I know my 29 quarts of 10w40 SL Durablend are ACEA A3 (the new SM is not Eek ).

Hey, here is a real winner:

Valvoline Synpower 5w40 Cool :
SM/SL
ACEA A3/B3/B4
Mercedes Benz 229.3
VW 502.00 and 505
BMW Long Life 01
Zinc 1020 ppm
Phosphorus 900 ppm
Calcium 3300 ppm
Last edited by tallpaul
quote:
Any info on this process with regard to parameters when specifiying an oil.

It depends "who is the boss". Sometimes it's marketing, sometimes the lube engineers, somtimes the engine developers, these days the catalyst guys want to change the oil.

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How about short cycle and long weekend blast.

That really seems to be the very best method to kill the oil. I have not seen a more effective way. It's similar to police driving, which is the worst case driving condition for gasoline engines in Europe.

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Car use and maintenace of car re fuelling etc may have a more significant effect on wear rather than the oil itself!

Yes.

@TallPaul
That's the way to select a good oil - look at specifications. Forget the amount elements. It's like saying: This picture has such an amount of red colour, green colour, blue colour - this must be a good picture. If it is from Picasso or from your 4 year old daughter - how do you know???
I saw a bit different result in a testing program .

The Mobil 0w-40 made both more horsepower on a engine dyno and had less amounts in particle counts in same engine , back to back testing vs Castrol SLX 0w-30 .

Not saying your wrong Callisa , just posting what I saw from another test .

That 0w-40 Mobil is really something else IMO . It meets both GM LL specs and the LL-01 .

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Originally posted by Callisa:

Well, I have seen two engine having run on a dyno under same test conditions, one with Mobil 1 0W-40 and one with a german version of Castrol Syntec 0W-30.

Mobil 1 is good, but Castrol is (at least in this engine, within this test) clearly the winner. Better piston cleanliness, better wear performance.
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The Mobil 0w-40 made both more horsepower on a engine dyno and had less amounts in particle counts in same engine , back to back testing vs Castrol SLX 0w-30 .

Particles where not counted in that test. The difference in the power output could be explained with the standard deviation of the dyno test rig or a different atmospheric pressure. Can you exclude that in your testing?
Besides, one oil does not have to work good in all engines designs if it works well in one.
quote:
Originally posted by Callisa:
quote:
How about short cycle and long weekend blast.

That really seems to be the very best method to kill the oil. I have not seen a more effective way. It's similar to police driving, which is the worst case driving condition for gasoline engines in Europe.

I often hear folks ask what to do about a short trip vehicle and the typical advice is to take it on a long freeway run periodically. So that does not really help? I have such a vehicle ('92 Aerostar 3.0) and have turned to trying synthetic oil in it for the typical 4000 miles per year.

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