Is there any known empirical evidence in support of the assertion, a higher grade/thicker oil will protect an engine better, rather then the chemistry of the oil itself? In other words, is the suppression of engine wear contingent on the chemical formulation of an engine oil, or it's thickness?
Does thicker oil=better protection?
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JHZR2
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Both. Time to read about hydrodynamic lubrication... But adds look to be at least 50% important at ensuring good performance over the lifecycle. Lubrication and chemical stability are two different things. Ep/aw is another.
Originally Posted By: JHZR2
Both. Time to read about hydrodynamic lubrication... But adds look to be at least 50% important at ensuring good performance over the lifecycle. Lubrication and chemical stability are two different things. Ep/aw is another.
I'll get on it. Thanks!
Both. Time to read about hydrodynamic lubrication... But adds look to be at least 50% important at ensuring good performance over the lifecycle. Lubrication and chemical stability are two different things. Ep/aw is another.
I'll get on it. Thanks!
Originally Posted By: JHZR2
Both. Time to read about hydrodynamic lubrication... But adds look to be at least 50% important at ensuring good performance over the lifecycle. Lubrication and chemical stability are two different things. Ep/aw is another.
Hi,
JHZR2 - I agree. Perhaps a good but old example of this is the orginal Morris Mini-Austin 850 of 1959. This used a combined engine-gearbox and the components survived very well individually on the 20W-20, 20W-30 or 10W-30 lubricants of the era. The combined engine-gearbox required a more robust viscosity lubricant, and the 20W-50 viscoity was developed by Duckhams for this purpose (later followed by Castrol etc)
In my role I had a lot of experience with early versions (export prototypes) of these vehicles and they did not tolerate lighter viscosities of any Brand or formulation!
Of course the real problem was excessive permanent shear which caused excessive wear on many components (synchronisers, bearings etc) and almost legendary leaking at various joints. And this was at a time when 1000-1500 mile OCIs were almost mandatory and these BMC engines used felt FF oil filters of high quality too!
In my experience it is always best to use the lowest viscosity lubricant recommended by the Manufacturer for the application
Both. Time to read about hydrodynamic lubrication... But adds look to be at least 50% important at ensuring good performance over the lifecycle. Lubrication and chemical stability are two different things. Ep/aw is another.
Hi,
JHZR2 - I agree. Perhaps a good but old example of this is the orginal Morris Mini-Austin 850 of 1959. This used a combined engine-gearbox and the components survived very well individually on the 20W-20, 20W-30 or 10W-30 lubricants of the era. The combined engine-gearbox required a more robust viscosity lubricant, and the 20W-50 viscoity was developed by Duckhams for this purpose (later followed by Castrol etc)
In my role I had a lot of experience with early versions (export prototypes) of these vehicles and they did not tolerate lighter viscosities of any Brand or formulation!
Of course the real problem was excessive permanent shear which caused excessive wear on many components (synchronisers, bearings etc) and almost legendary leaking at various joints. And this was at a time when 1000-1500 mile OCIs were almost mandatory and these BMC engines used felt FF oil filters of high quality too!
In my experience it is always best to use the lowest viscosity lubricant recommended by the Manufacturer for the application
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A thicker oil can't give added protection
if it's not required in fact it will be counter-productive in that goal. Hence the lubrication axiom, "as thin as possible, as thick as necessary".
To know if a thicker oil is necessary one needs to know first what the minimum viscosity requirements are for your engine. That will take some research beyond what the average owner wants to do but it's likely in the 3.5-4.0cP range. Then you'll need a way of measuring it your vehicle while it's running. Oil preasure and temperature gauges will help in that regard. If you're still with me, send me a PM and we'll take it from there.
Since most owners are not interested in getting into motor oil in that much detail, it's safe to say, running the lightest oil recommended by the manufacturer, as Doug Hillary suggested, particularly for street use, will provide an oil that's as thick as you'll ever need and then some.
if it's not required in fact it will be counter-productive in that goal. Hence the lubrication axiom, "as thin as possible, as thick as necessary".
To know if a thicker oil is necessary one needs to know first what the minimum viscosity requirements are for your engine. That will take some research beyond what the average owner wants to do but it's likely in the 3.5-4.0cP range. Then you'll need a way of measuring it your vehicle while it's running. Oil preasure and temperature gauges will help in that regard. If you're still with me, send me a PM and we'll take it from there.
Since most owners are not interested in getting into motor oil in that much detail, it's safe to say, running the lightest oil recommended by the manufacturer, as Doug Hillary suggested, particularly for street use, will provide an oil that's as thick as you'll ever need and then some.
The one thing you'll learn very quickly is that everyday thinking, doesn't always match up with the science and testing have shown.
When in doubt, trust the manufacturers recommendations.
When in doubt, trust the manufacturers recommendations.
JHZR2
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... And don't get caught up in the stupid "real synthetic" argument.
Originally Posted By: JHZR2
... And don't get caught up in the stupid "real synthetic" argument.
I don't know if you caught the latest issue of Popular Mechanics. They informed readers that synthetics "are really just natural oil refined to a much higher degree, with more complex additive packages for improving performance in both everyday and extreme conditions."
They also quoted Ron Sullivan, the technology manager of Pennzoil: "For most applications, stick with the manufacturer's recommended oil." He went on to note synthetic oil's benefits, but mentioned that those tend to appear under extreme conditions, including high heat towing, turbos, and the usual suspects. That's when he suggested that synthetics might be useful. "And synthetics are better at that."
PM concluded their article by saying, "These are bold claims and may be worth considering when choosing oil, but we can't remember the last time an engine failed on conventional oil, so going synthetic when you don't have to may be a waste of money. If you abuse your engine, consider synthetics; otherwise follow the manufacturer's suggestion."
Ref: PM, Vol. 189. No. 7, P 127
... And don't get caught up in the stupid "real synthetic" argument.
I don't know if you caught the latest issue of Popular Mechanics. They informed readers that synthetics "are really just natural oil refined to a much higher degree, with more complex additive packages for improving performance in both everyday and extreme conditions."
They also quoted Ron Sullivan, the technology manager of Pennzoil: "For most applications, stick with the manufacturer's recommended oil." He went on to note synthetic oil's benefits, but mentioned that those tend to appear under extreme conditions, including high heat towing, turbos, and the usual suspects. That's when he suggested that synthetics might be useful. "And synthetics are better at that."
PM concluded their article by saying, "These are bold claims and may be worth considering when choosing oil, but we can't remember the last time an engine failed on conventional oil, so going synthetic when you don't have to may be a waste of money. If you abuse your engine, consider synthetics; otherwise follow the manufacturer's suggestion."
Ref: PM, Vol. 189. No. 7, P 127
It may be. But what are oil temps and pressure reading after the modifications vs before?
Originally Posted By: supercity
What about for a modified engine? Is thicker oil required?
Say engine X is a 2L, 4 cylinder, turbocharged and makes 250hp. With more boost and or rpm it now makes 350hp. Would a higher grade be benificial?
Oh yes! As you go with bigger turbos that have a higher boost threshold, the amount of heat generated by the turbo goes up. As that rises, so does your oil temperature. As oil temps rise, your relative viscosity drops, making thicker oil a necessity. In addition, the foil bearing that connects the exhaust turbine and compressor spins pretty fast-a shear stable oil works very well in these conditions.I'm getting tired of writing why thicker oil is good, so here's a good example:
There was a thread on BITOG not too long ago where they needed advice for a '87 Buick GNX that was heavily modded. I don't think how much power it made actually came up, but the oil temperature was reaching about 270f! Most every answer was some sort of 20w-50 or similar oil.
What about for a modified engine? Is thicker oil required?
Say engine X is a 2L, 4 cylinder, turbocharged and makes 250hp. With more boost and or rpm it now makes 350hp. Would a higher grade be benificial?
Oh yes! As you go with bigger turbos that have a higher boost threshold, the amount of heat generated by the turbo goes up. As that rises, so does your oil temperature. As oil temps rise, your relative viscosity drops, making thicker oil a necessity. In addition, the foil bearing that connects the exhaust turbine and compressor spins pretty fast-a shear stable oil works very well in these conditions.I'm getting tired of writing why thicker oil is good, so here's a good example:
There was a thread on BITOG not too long ago where they needed advice for a '87 Buick GNX that was heavily modded. I don't think how much power it made actually came up, but the oil temperature was reaching about 270f! Most every answer was some sort of 20w-50 or similar oil.
Oil pressure and temperature gauges are importance for modified engines and for track cars to fine tune oil grade. But for most drivers on public roads, manufacturer's recommended oil is more than adequate.
Originally Posted By: dave1251
It may be. But what are oil temps and pressure reading after the modifications vs before?
Well for the sake of this arguement the oil temp would be kept the same or "within limits" by adding a larger oil cooler if needed.
The point is, if the engine is now asked to rev to say, 30% higher and or have 30% higher cylinder pressure (more boost) how is this going to influence the oil viscosity requirements.
It may be. But what are oil temps and pressure reading after the modifications vs before?
Well for the sake of this arguement the oil temp would be kept the same or "within limits" by adding a larger oil cooler if needed.
The point is, if the engine is now asked to rev to say, 30% higher and or have 30% higher cylinder pressure (more boost) how is this going to influence the oil viscosity requirements.
Hmmm, I like this question, but you mitigated the heat factor for the need of a higher grade of oil with a oil cooler. The other factor is oil pressure which if the engine is maintaining specifications at operations, I would not use a higher grade of oil. I do not see a need for it, now I would send a UOA after a short run to determine a conservative OCI and to confirm my selection of oil grade is sufficient, for making the determination for oil grade the biggest wear metals I would look out for are lead, copper, and then iron.
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Originally Posted By: CATERHAM
running the lightest oil recommended by the manufacturer,
My owner`s manual lists 10W30 as "preferred" (which is the thinnest recommended viscosity for my car). The FSM lists 10W30-20W50. Then there`s a sticker under the hood that says 10W is preferred and lists 10W30 and 10W40 only.
Would 10W30 be the best of the best? Any advantage running 10W40 vs 10W30? What would be the pros and cons of each viscosity listed in all 3 sources (manual,fsm,and the under hood sticker)?
running the lightest oil recommended by the manufacturer,
My owner`s manual lists 10W30 as "preferred" (which is the thinnest recommended viscosity for my car). The FSM lists 10W30-20W50. Then there`s a sticker under the hood that says 10W is preferred and lists 10W30 and 10W40 only.
Would 10W30 be the best of the best? Any advantage running 10W40 vs 10W30? What would be the pros and cons of each viscosity listed in all 3 sources (manual,fsm,and the under hood sticker)?
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Wouldn't this all depend on built specs like clearances, etc before deciding on oil weight? That's what I was told by my builder whom I trust.
Originally Posted By: aquariuscsm
Originally Posted By: CATERHAM
running the lightest oil recommended by the manufacturer,
My owner`s manual lists 10W30 as "preferred" (which is the thinnest recommended viscosity for my car). The FSM lists 10W30-20W50. Then there`s a sticker under the hood that says 10W is preferred and lists 10W30 and 10W40 only.
Would 10W30 be the best of the best? Any advantage running 10W40 vs 10W30? What would be the pros and cons of each viscosity listed in all 3 sources (manual,fsm,and the under hood sticker)?
Those oil grade recommendations are almost 20 years old and are for mineral oil. So what are the viscosity characteristics of a 20 year 10W-30 dino oil? Well for starters any modern 5W-30 synthetic will provide better overall lubrication.
If you're concerned about the possibility of high oil temp's in a` Texas summer rely on your oil pressure readings (I believe the 300ZX has an OP gauge) to determine if you actually require something heavier than a 5W-30 syn. If you can still maintain 65 psi at 6,500 rpm with the oil as hot as it ever gets then you don't require nor will you benefit from anything heavier.
Originally Posted By: CATERHAM
running the lightest oil recommended by the manufacturer,
My owner`s manual lists 10W30 as "preferred" (which is the thinnest recommended viscosity for my car). The FSM lists 10W30-20W50. Then there`s a sticker under the hood that says 10W is preferred and lists 10W30 and 10W40 only.
Would 10W30 be the best of the best? Any advantage running 10W40 vs 10W30? What would be the pros and cons of each viscosity listed in all 3 sources (manual,fsm,and the under hood sticker)?
Those oil grade recommendations are almost 20 years old and are for mineral oil. So what are the viscosity characteristics of a 20 year 10W-30 dino oil? Well for starters any modern 5W-30 synthetic will provide better overall lubrication.
If you're concerned about the possibility of high oil temp's in a` Texas summer rely on your oil pressure readings (I believe the 300ZX has an OP gauge) to determine if you actually require something heavier than a 5W-30 syn. If you can still maintain 65 psi at 6,500 rpm with the oil as hot as it ever gets then you don't require nor will you benefit from anything heavier.
Originally Posted By: Jim Allen
Amen Caterham! The only issue I see with 5W30 vs 10W30 is the possibility of more shearing. That seems to be less and less a danger these days.
Hi Jim.
That observation can still apply for mineral oils.
But when comparing the high temperature protection of a 5W-30 synthetic to 10w-30 dino, the 5W-30 syn is far superior.
Amen Caterham! The only issue I see with 5W30 vs 10W30 is the possibility of more shearing. That seems to be less and less a danger these days.
Hi Jim.
That observation can still apply for mineral oils.
But when comparing the high temperature protection of a 5W-30 synthetic to 10w-30 dino, the 5W-30 syn is far superior.
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