Why use thicker oil?

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Hi,
Tim - I seem to have hijacked this Thread - it was not intended

ILSAC's GF-4 minimum standards are "minimum"

For instance 10W-30 viscosity and upwards under GF-4 only need to show less than half the fuel efficiency (D6837) displayed by 0W-20 and 5W-20 viscosity lubricant after 96 hours aging and less than half after 16 hours. This opens up a different scenario

As well Shear Stability is measured @ 100C after a 10 hours
period.

Other viscosity matters such as HTHS must remain as per J300 such as, 2.9cP for 0W-40, 5W-40 and 10W-40 multigrades and 3.7cP for such as 5W-50!

So all multigrade lubricants having an initial designation of 0W, 5W or 10W could meet GF-4 - with some compromises

This is why the ACEA quality designations are at least meaningful IMO - and they perhaps spell out the HTHS viscosity minimums a little more clearly
 
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Don't forget the enhanced splash properties of thinner viscosities.

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This thread has discussed high HTHS oil in reference to operating temperatures. Another factor in specifying a high HTHS oil would be physical shearing.

Case in point would be the Honda CB1 I owned. It had a straight cut gear train operating the dual overhead camshafts (13,000 rpm red line). Original oil used was Castrol 20W50. It sheared down to less than 20 wt. in 500 mi usage. A higher HTHS oil was used, Mobil 1 15W50, and survived for 3000 mi OCI with little degradation. Oil temperature was controlled via a large sump, and was not a factor in this case.
 
An oil thins under high shear stress. An oil thickens under pressure. This is partly why HTHS is only one of a hundred things that make an oil work in a SI engine. It is only one parameter but people talk about it as if it is a panacea. If an oil had a HTHS of 4.0 and no additives it would result in much higher wear rates than if it was fully formulated.

aehaas
 
Originally Posted By: Doug Hillary
Hi,
OVERK1LL - Firstly, I would use the upper end of Ford's viscoity recommendations for the engine if wanting to go with the most viscous lubricant "allowed". Synthetics in this range with Ford's endorsement are great lubricants. Ford have had nearly two decades of experience with low viscosity lubricants in their engines - I have not read any negative exposure to this in the form of Warranty claims and the like! Where heavier viscoities are specified in other World markets for the same engine - the same comments apply. The low viscosity lubricants work well where they are specified by the engine's maker!

Secondly I would consider M1 0W-40. M1 TDT 5W-40 or Delvac 1 5W-40 are quite viscous SAE40 lubricants and they would work well in this engine too but they may be outside Ford's allowable range of viscosities

If I owned such an engine, was living in a hot climate and "using" the uppermost performance from the engine, (and wanting to use a "suitable" SAE40 lubricant) I would use any of the lubricants noted above starting with M1 0W-40


Doug:

Hopefully we are picking this up tomorrow. I will post what it states in the manual. I have been thinking over the 0w40 thing........

-Chris
 
My saturn SC2 1.9l is rated for 5W-30, would this car benefit from a 5w-40 oil? Some here have said that the GM engines like 40W oils, here in North Cali, we tend to have milder weather, car gets used both for short trips and long interstate drives. Would the 40W have better protection for extended runs while having a minor impact on fuel mileage. Looks to me like this thin/thick debate is more engine specific than having a one fits all solution across the board.
 
Originally Posted By: kgb007stb
My saturn SC2 1.9l is rated for 5W-30, would this car benefit from a 5w-40 oil? Some here have said that the GM engines like 40W oils, here in North Cali, we tend to have milder weather, car gets used both for short trips and long interstate drives. Would the 40W have better protection for extended runs while having a minor impact on fuel mileage. Looks to me like this thin/thick debate is more engine specific than having a one fits all solution across the board.


Mine ran fine on 30W oils and I doubt there would be much difference. I did however use both M1 0W-40 and 10W-40 MaxLife in it in and effort to control the burning for which these engines can be notorious for. But for no other reason than that. Mine burned about a quart every 3K, which was a little more than my liking...

I did however once get 40mpg using GC 0W-30 in it though when I was driving quite a bit...
 
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Originally Posted By: AEHaas
An oil thins under high shear stress. An oil thickens under pressure. This is partly why HTHS is only one of a hundred things that make an oil work in a SI engine. It is only one parameter but people talk about it as if it is a panacea. If an oil had a HTHS of 4.0 and no additives it would result in much higher wear rates than if it was fully formulated.

aehaas


I agree completely. BUT, if you use an oil that is fully formulated, and has a HTHS of 4, you get fantastic wear rates as in 2,000,000 miles in 19 years on many different vehicles. Two of the vehicles called for 5W-20. One had 190,000 +/- and the other had 180,000 +/- on 15W-50 when they were traded just this year.
 
Originally Posted By: FrankN4


I agree completely. BUT, if you use an oil that is fully formulated, and has a HTHS of 4, you get fantastic wear rates as in 2,000,000 miles in 19 years on many different vehicles. Two of the vehicles called for 5W-20. One had 190,000 +/- and the other had 180,000 +/- on 15W-50 when they were traded just this year.


I have seen many vehicles go 150-200k easily with 5w30 or 10w30 dino. My best friend runs all his vehicles past 200k (some 300k) with Supertech 5w20 & 5w30. So 15w50 would be overkill IMO. Just traded in a Lexus V6 with over 150k on 5w30 5000 OCI of which 1/2 was valvoline all climate & the last 75k was PP. The engine was perfect and used 1/3 qt of oil every 5000. So, saying that a modern engine (exclude GM garbage) going over 150k is some big feat is meaningless. Show me one with 350-400k on it and I'll take notice.

BTW, FWIW I will take cold start flow over HTHS any day of the week...especially in the wife & daughters daily drivers that get started and have 15-30 seconds to pump up to pressure before they hit the throttle. Cold start wear is the killer of the engines driven by the ladies IMO
 
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Originally Posted By: PT1
Originally Posted By: FrankN4


I agree completely. BUT, if you use an oil that is fully formulated, and has a HTHS of 4, you get fantastic wear rates as in 2,000,000 miles in 19 years on many different vehicles. Two of the vehicles called for 5W-20. One had 190,000 +/- and the other had 180,000 +/- on 15W-50 when they were traded just this year.


I have seen many vehicles go 150-200k easily with 5w30 or 10w30 dino. My best friend runs all his vehicles past 200k (some 300k) with Supertech 5w20 & 5w30. So 15w50 would be overkill IMO. Just traded in a Lexus V6 with over 150k on 5w30 5000 OCI of which 1/2 was valvoline all climate & the last 75k was PP. The engine was perfect and used 1/3 qt of oil every 5000. So, saying that a modern engine (exclude GM garbage) going over 150k is some big feat is meaningless. Show me one with 350-400k on it and I'll take notice.

BTW, FWIW I will take cold start flow over HTHS any day of the week...especially in the wife & daughters daily drivers that get started and have 15-30 seconds to pump up to pressure before they hit the throttle. Cold start wear is the killer of the engines driven by the ladies IMO


If your engine takes more than 2 seconds to "pump up", you have issues

Honestly, if the oil flows and you get pressure within a second (which I always have, even with a 20-50 in winter), what's the advantage of better cold flow other than gas mileage while the oil is warming up?

Higher HTHS has been proven to protect better as the GM 3.8L test have shown. For someone like me whose car spends the better part of it's life warmed up, give me higher HTHS any day.

Just because some engines live a long life on 5-30 doesn't make 15-50 "overkill". The engine may live a better life in it's old age in the form of less oil consumption, better compression, and better mileage due to better compression using the heavier oil.
 
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