Selecting thickness of oil?

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What would be a good criteria--oil pressure, type of driving, used oil analysis, mechanical noise of engine, etc.?

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Yes.

A Dino 10W40 could be a 10W30 very quickly. If at stage of oil burning then why bother even with oil change? Castrol GTX 15W40 HTHS is 4 compared to high mileage at 4.8, so this may be an answer to changing vis.

Oil pressure is interesting as Classic Car owners just love high oil pressure an add additives to keep it high, which IMO is a nonsense as changes to usual oil pressure is an indication of potential problems or immediate if oil pipe comes off!

UOAs interesting but are they of any real value, many just say this oil could last longer but its been changed anyway.

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Originally posted by Callisa:

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What would be a good criteria--oil pressure, type of driving, used oil analysis, mechanical noise of engine, etc.?

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Yes.

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Sorry, I forgot to mention oil temperature.

BTW, some people say they put thicker oil in and find the engine runs a lot quieter.

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Originally posted by MGBV8:
UOAs interesting but are they of any real value, many just say this oil could last longer but its been changed anyway.

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UOA is good to see if your oil change interval length is appropriate. I did one on my F150 and found I should be able to go 5000 miles, not 3000. So I will try 5000 next time and do another UOA. If that UOA is good I will continue the 5000 mile OCIs.

Re Noise Synlube, if I recollect correctly, use the solids as noise reduction, so I wonder if some ois have a noise reduction agent to make the engine sound less noisy so you continue to buy oil. Opposite is M1 which can be noisey but provides the protection.

Engine is fine with 25 hot at still , 40-60 at speed . 30-60 lbs better and above 30 still loose value in performance of engine . Still pressure down from 30 to 25 at 5 thousand kilometer change oil . Adjust that way .

Mobil need additional lubricity to be perfect . Adding good mineral oil or ester possible .

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Originally posted by Char: Mobil need additional lubricity to be perfect . Adding good mineral oil or ester possible .

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IIRC: There are some UOAs at the bobistheoilguy.com forums where someone ran 4 qts Mobil 1 with 1 qt Redline (esters) and the UOA looked better than when he ran straight Mobil 1.

I noticed M1 10w30 lists 100C vis at about 10 cSt, whereas the Valvoline Synpower is 1.9. Mobil 1 seems to run on the thin side for some reason.

M1 probably stopped on price grounds, rather than produce ultimate oil, because esters are expensive and any added protection would probably not be noticeable on a general road car.

Adding GIII mineral as per Castrol may produce a good all round oil at reduced cost, problem is GIII has a bad name since the case.

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Originally posted by TallPaul:
[QUOTE] whereas the Valvoline Synpower is 1.9. Mobil 1 seems to run on the thin side for some reason.

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Oops. My previous post should have said "Synpower is 10.9"



One fellow at the oil guy site is promoting oil thickness selection by running as thin of an oil as you can until you get down to the level of 10 psi per 1000 rpm. What do you think to that method, Callisa?

My feeling is it contradicts many manufacturer specified oil pressures, such as early to mid-90s Fords, most of which spec 40-60 psi at 2000 rpm.

[QUOTE]Originally posted by MGBV8:
M1 probably stopped on price grounds, rather than produce ultimate oil, because esters are expensive and any added protection would probably not be noticeable on a general road car.[QUOTE] I wonder if added protection from esters is more noticable with a Group I through III oils. Also, I am thinking just a little bit, maybe one ounce Redline per quart, would help cold starting and reduce wear (albeit, perhaps not to a significant degree), but also have a cleaning effect or at least deposit prevention effect. At any rate, that small of an amount (one oz per qt) may help, can't hurt.

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One fellow at the oil guy site is promoting oil thickness selection by running as thin of an oil as you can until you get down to the level of 10 psi per 1000 rpm. What do you think to that method, Callisa?

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Borderline. Very borderline. But very interesting approach.

Thank You Callisa, you have confirmed what I believed to be the case. One poster said the 10 psi per 1000 rpm applies only to max RPM and that it is OK to be higher than that at mid RPMs. So I think this 10 per 1000 rule of thumb has been distorted and abused along the way.

IMO Mineral is probably better than PAO apart from cold flow and hot situations, and the crud left behind. PAO needs something to make up for disadvantages and these are esters, AN ior even GIII, reason why GC has rave reviews. AT a guess Castrol may say have 50% PAO & esters and 50% GIII so becoming a true Synth.

Esters help PAO but may have less of an effect with mineral as they have more of the same charecteristics, but then there is Magnatec, the enigma!.