Oil viscosities

Recently I had an experienced auto service guy that has owned his own shop for many years tell me that I should not be using 5W-30 in my Silverado as the factory suggests, even though I have 145K on it with no oil related problems. He said that when he does an oil change he puts

20W-50 in all vehicles. I was a little surprised that he would advise contrary to factory recommendations. He showed me an article from about ten ago that said 30W oil does not protect an engine at normal operating temps. This did not seem reasonable to me. If that were the case I would imagine a lot more engine failures would be happening. Comments?
Reply to
Mike Copeland
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I have a Word .doc with specs which I can't post because they would be all over the page. I'll post the text and delete the specs. If it sounds interesting enough e-mail me and I'll send you the .doc. (I got is some time back from a Ford N/G. I've been using Valvoline Racing

20/50 with my 4.6 Ford (T-Bird) and at 140 K it's still running beautifully.

Heres the text: Very few manufactures recommend 10W-40 any more, and some threaten to void warranties if it is used. It was not included in this article for that reason. 20W-50 is the same 30 point spread, but because it starts with a heavier base it requires less viscosity index improvers (polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-40 with no viscosity index improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new

10W-30. Follow your manufacturer's recommendations as to which weights are appropriate for your vehicle.

Viscosity Index is an empirical number indicating the rate of change in viscosity of an oil within a given temperature range. Higher numbers indicate a low change, lower numbers indicate a relatively large change.

The higher the number the better. This is one major property of an oil that keeps your bearings happy. These numbers can only be compared within a viscosity range. It is not an indication of how well the oil resists thermal breakdown.

The Data:

Listed alphabetically --- indicates the data was not available

Brand VI Flash Pour %ash %zinc

20W-50 AMSOIL 136 482 -38
Reply to
F.H.

Paraphrased the owners manual for my 2003 Chevy specifically says do not use SAE10-40 or SAE20-50 grade oils, use will void warranty. The tolerances are much tighter in today's engines and the top end of the engine will not receive enough oil. As for 30W not being enough, unless you really drive it hard. red line hard and loaded constantly, 30W is good oil. I've never read or heard of 30W not protecting an engine in normal climates. Desert conditions might be different, but in the service we never ran anything but 30W in everything,

1/4 ton jeeps to 60 ton main battle tanks, even the 72 ton M88 tank recovery vehicle with its hot running V-12 air cooled Allison gas engine only got 30W. It has been very hard for a guy who has used nothing but 20-50, 50, and even Kendal Nitro 70 in one engine, to adapt to something as thin as 5-30. But I figure if GM was willing to warranty the thing till it hits 88,000 miles, I would do what they want. (Yeah I know, I bought a 60,000 mile $100 deductible extended warranty from GM, and probably wont need it, but as my grandfather used to say when I didn't want to bring a jacket on fishing trips, "If you don't need it you can take it off, if you don't have it, you cant put it on"). Whitelightning
Reply to
Whitelightning

Thicker oil=better protection but worse economy...

What's everyone's thinking on that?

Reply to
Shades

Reply to
Frank S.

here is my 2 cents worth, I use Castrol GTX 10W-30 in my GMC Envoy, and the GMC Seria PU before the Envoy, the truck over 150 K miles, the Envoy 107 K as of now, and no oil related probs to date.

Reply to
Craig M

"" wrote: > Mike Copeland wrote: > > Recently I had an experienced auto service guy that has > owned his own > > shop for many years tell me that I should not be using 5W-30 > in my > > Silverado as the factory suggests, even though I have 145K > on it with no > > oil related problems. He said that when he does an oil > change he puts > > 20W-50 in all vehicles. I was a little surprised that he > would advise > > contrary to factory recommendations. He showed me an article > from about > > ten ago that said 30W oil does not protect an engine at > normal operating > > temps. This did not seem reasonable to me. If that were the > case I would > > imagine a lot more engine failures would be happening. > > Comments? > > I have a Word .doc with specs which I can't post because they > would be > all over the page. I'll post the text and delete the specs. > If it > sounds interesting enough e-mail me and I'll send you the > .doc. (I got > is some time back from a Ford N/G. I've been using Valvoline > Racing > 20/50 with my 4.6 Ford (T-Bird) and at 140 K it's still > running beautifully. > > Heres the text: > Very few manufactures recommend 10W-40 any more, and some > threaten to > void warranties if it is used. It was not included in this > article for > that reason. 20W-50 is the same 30 point spread, but because > it starts > with a heavier base it requires less viscosity index improvers > > (polymers) to do the job. AMSOIL can formulate their 10W-30 > and 15W-40 > with no viscosity index improvers but uses some in the 10W-40 > and 5W-30. > Mobil 1 uses no viscosity improvers in their 5W-30, and I > assume the new > 10W-30. Follow your manufacturer's recommendations as to which > weights > are appropriate for your vehicle. > > Viscosity Index is an empirical number indicating the rate of > change in > viscosity of an oil within a given temperature range. Higher > numbers > indicate a low change, lower numbers indicate a relatively > large change. > > The higher the number the better. This is one major property > of an oil > that keeps your bearings happy. These numbers can only be > compared > within a viscosity range. It is not an indication of how well > the oil > resists thermal breakdown. > > The Data: > > Listed alphabetically --- indicates the data was not available > > Brand VI Flash Pour %ash %zinc > > 20W-50 > AMSOIL 136 482 -38 Castrol GTX 122 440 -15 .85 .12 > Exxon High Performance 119 419 -13 .70 .11 > Havoline Formula 3 125 465 -30 1.0 --- > > snip / / / / / / / > > All of the oils above meet current SG/CD ratings and all > vehicle > manufacture's warranty requirements in the proper viscosity. > All are > "good enough", but those with the better numbers are icing on > the cake. > > The synthetics offer the only truly significant differences, > due to > their superior high temperature oxidation resistance, high > film > strength, very low tendency to form deposits, stable viscosity > base, and > low temperature flow characteristics. Synthetics are superior > lubricants > compared to traditional petroleum oils. You will have to > decide if their > high cost is justified in your application. > > The extended oil drain intervals given by the vehicle > manufacturers > (typically 7500 miles) and synthetic oil companies (up to > 25,000 miles) > are for what is called normal service. Normal service is > defined as the > engine at normal operating temperature, at highway speeds, and > in a dust > free environment. Stop and go, city driving, trips of less > than 10 > miles, or extreme heat or cold puts the oil change interval > into the > severe service category, which is 3000 miles for most > vehicles. > Synthetics can be run two to three times the mileage of > petroleum oils > with no problems. They do not react to combustion and > combustion > by-products to the extent that the dead dinosaur juice does. > The longer > drain intervals possible help take the bite out of the higher > cost of > the synthetics. If your car or bike is still under warranty > you will > have to stick to the recommended drain intervals. > > These are set for petroleum oils and the manufacturers make no > official > allowance for the use of synthetics. > > Oil additives should not be used. The oil companies have gone > to great > lengths to develop an additive package that meets the > vehicle's > requirements. Some of these additives are synergistic, that is > the > effect of two additives together is greater than the effect of > each > acting separately. If you add anything to the oil you may > upset this > balance and prevent the oil from performing to specification. > > The numbers above are not, by any means, all there is to > determining > what makes a top quality oil. The exact base stock used, the > type, > quality, and quantity of additives used are very important. > The given > data combined with the manufacturer's claims, your personal > experience, > and the reputation of the oil among others who use it should > help you > make an informed choice.

Nice comment but I believe you left on one important factor about oil viscosity. The lower the rating (ie 10w30 vs 20w50) the less power that is required to shear in it the bearings and from the cylinders walls so the less power in loss. (shearing is normal and not to be confused with film strength or rupture) It is very foolish to use

20w50 in a modern engine unless the temps are above 100F a lot and even then 15w40 is not than enough here. You are not lubing any better than with a good 10w30 oil (actually worse in some ways) and not extending your engines life over a good 10w30 oil. I have seen some engines with a bit of wear actually use more 20w50 oil than 15w40. Also, the reason that Detriot no longer recommands 10w40 because they had a lot of trouble (particularly GM) with teh VI in Dino 10w40 oil cooking out and causing the rings to stick.
Reply to
SnoMan

5-30.
10w40 Dino oil is about the worst stuff you can put is a modern engine. the VI in the oil cooks out in the rings and 20w 500 is same way and too thick too. If you are neverous about some high temps, use striaght 30 oil (it will potect better than 10w30 and 10w30 has better high temp perfomance than 5w30 (because it has less VI in it and straight 30 has none).
Reply to
SnoMan

My 92 Dodge owner's manual (360 gas engine) says, "Never use 10W-40 in this engine." Only straight 30W and 10W-30 are recommended unless you are in a very low temperature climate.

What I'd like to know, is what is the difference between 5W-30 and 10W-30 in high temperature? Shouldn't they be the same?

Al

Reply to
Big Al

When I owned a 91 F150 I tried running 20w50 in the hot desert summers. Indeed it did use much more oil than when I ran 10w40...

DJ

Reply to
DJ

From a purely theoretical point of view. do you think your service guy knows more about engine lubrication than the engineers that design engines for a living? Apart from voiding the warranty by using the wrong oil, there are other considerations.

Ford engines have been known to fail when lubed with higher viscosity oils because the drain back rate to the pan is too low to keep the valve covers from filling up with oil. With most of the oil in the top of the engine, the oil pump pick-up sucks air causing a loss of oil pressure and bearing failure.

Randy

Reply to
R. O'Brian

The only time I ever seen this was back when I circle raced boats. The G force in the turns would push all the oil up into the valve covers. There were lots of tricks to prevent it, gates etc.. We also used to insert reducers (old trick) into the oil galley going up to the rockers on big block Chevy's to divert oil pressure to the crank.

I think if one warms up the engine for a minute the oil thins enough to avoid this scenario.

Reply to
F.H.

Thx for all the great posts. I have been using Castrol 5W-30 (now I use the "High Mileage") since the truck was new. I think it's time to find a new service shop. Mike

Reply to
Mike Copeland

The difference is the amount of VI used (Viscosity Improver) in the oil. 5w30 has more and VI actually takes a little away for the oil lubrication properties and 5w 30 tends to thin out more at high temps because of the VI. THe oil is tested at 0F and at 210F and has to fall within a certian range of flow rate at those temps to be rated a certain grade (it is a fairly wide range). THey do not test it at other temps and the oil in engine bearing and rings can get a lot hotter than 210 in your engine at times and oils with higher concentrations of VI tend to thin out even more at high temps as time goes on.

Reply to
SnoMan

My uncle is a motor monkey from way back. I have an 86 chev 1/2 ton, it had a 6 cyl when I bought it, which was showing signs of maltreatment. He recommended I use a heavier weight oil, rather than spend any money rebuilding the motor, saying they were built pretty tough. Unfortunately I had a rad failure on the highway and the engine overheating idiot light wasn't working. I didn't smell the coolant until it was too late and smoked that motor. Next up was a 350 from a high-miler propane unit that leaks a bit and smokes a bit on startup. I tried heavier oils in the "new" motor, but it doesn't seem to like them as much as it likes 10W30. I buy the cheap stuff and use about a gallon between oil changes.

-JD

PS, also have been using Restore based on advice from this NG, with mixed success.

Reply to
John D

My brother-in-law had an 86 Ferrari mid-engine V-8. It had one main oil pump and two scavenger pumps, one for each Vee -- there specifically to prevent oil starvation and such. One thing bothered me with that little beauty: the oil filter was mounted above the engine block, between the heads, open end down. I could not figure out how to change the oil filter without making a mess, even with towels/rags galore.

Franko

higher viscosity oils

keep the valve covers

top of the engine,

pressure and bearing

raced boats. The

valve covers.

also used to

to the rockers

thins enough to

Reply to
Franko

THis comes as no surprize because of the increase force it take to shear 20w50 from cylinder walls and the slower rate at which it will drain back to from the oil scraper ring impeeding its function.

Reply to
SnoMan

Poke a hole in the top with a screw driver

Spud

Reply to
Spud

Yup, tried that. No effect. Tried poking a hole big enough for a thin clear hose to be slipped in to siphon/pump out the oil -- that worked the best. No Quickie Lubes, obviously.

had

the

the

change

towels/rags

Reply to
Franko

There is a "stand" pipe that reaches almost the bottom (or in this case top) of the filter whose function is to keep the filter from draining when the engine is shut off. so poking a hole wont work. chrysler slant six engines had the same set up. oil filter upside down on right side of engine. even nicer they put the oil filter adapter over the right side motor mount and is allowed to go bad enough, they would bust the adapters.

Whitelightning

Reply to
Whitelightning

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