Wrecked82

When I changed oil in early July, thought I would try 20W50 instead of the old 10W30. Since then, engine seems to be running somewhat hotter. Is it my imagination, or does a heavier weight contribute to engine heat?

mountainmotor

In my opinion yes it can.

Synthetics can also flow in a turbulent fashion dissipating more heat while maintaining their desired film strength. NON syns flow in a laminar fashion holding heat.

So the thinner a vicosity mineral oil you can use with out shearing it,the better off one will be. But,you will not know how much it has been sheared "as in a 10/40 sheared down to a 30wt unless you have it analyzed in which for 25 bucks"that all the shipping and detailed response" is a great way to actually know what's going on inside your engine. I recommend tdyson@argontech.com for the analyisis. He is a Tribologist and a Racer .If any of you ever choose to have your oil analyized,tell him Curtis sent you

I will edit and post a surprising amount of shear in very little miles with a common oil used by many and this was not in a high performance application

This engine is a 1994 Toyota Celica

Engine mileage, 39,000 , Miles on oil 1320. Car is used exclusively in city, stop and go, hot weather. Blackstone Labs (AC Delco filter Castrol 10W-40 GTX (dino)

AL 4

Chrom 0

Iron 2

Copper 3

Lead 1

Tin 0

Moly 101

Boron 299

Silicon 8

Sodium 3

Calcium 2056

Magnesium 10

Phos 845

Zinc 974

Barium 0

Antifreeze 0

Water 0

Magnanese, nickel, silver, titanium, potassium all 0

Visc: 65.4@210

Flashpoint 410

Fuel .5

Blackstone stated oil is doing well but did note the viscosity is barely 40. (Their acceptable range for 10W-40 is 65-76.)

The Viscosity is actually 11.79 cst@100 C so it is not a 40 wt. 9.3-12.5 is a 30wt.

Again,this oil only had 1320 miles on it!



[Modified by mountainmotor, 12:55 PM 8/13/2002]

Twin_Turbo

Also, multigrade oils w/ a low 2nd weight number have a lot of additives )polymers) that coil up when cold (so they're small) and have no or little effect on viscosity. When the oil gets hot they uncoil and becoime strands and do affect viscosity. This way the oil doesn't thin out too much. Additives don't lube! This especially applies to oils like 10W30 & so.

You can see it in the figures (cst = centistroke)

Marck

lars

Larry -
In addition the what mountainmotor states, there are a few other issues that should steer you away from running the heavier weight oil:

The SAE has obviously done quite a bit of testing on the subject matter of viscosity, and I'm on their mailing list. Their reseach indicates that for overall best performance and engine longevity, you want to run the THINNEST oil possible that will prevent metal-to-metal contact (the synthetics do an incredible job of this). Thinner oils produce less parasitic drag on the rotating components, so less energy (friction) is consumed in simply turning the engine. This produces less heat.

The other thing that is interesting is that an engine tends to "wear itself" to the "size" of the oil used. If you use a 20-50 oil in a perfectly good engine for no particular reason, you will actually see an initial increase in engine wear until the engine "wears itself to fit" the thicker oil.

Finally, the thinner oil puts less load on the oil pump, so the pump is easier to turn. This takes less power from the engine, producing more power at the rear wheels. When we were running competitively in NHRA, and if we needed an extra tenth on a "Banzai Run" to stay in the competition, we would drain the 30w out of the car and run 10w15 (this was before the era of synthetics). Pretty scary....

GrandSportC3

Very Interesting!!!!!!

GrandSportC3

Why is heavier oil used for racing???
For example - my engine builder recommends 10W40 for regular cruising and 20W50 for racing....

:cheers:

Olivier

Kingt

Larry, how much hotter are you talking about? While there is some heat transfer taking place in the oil, it's primary function is lubrication and preventing metal to metal contact.

DELTA DART

OhhhhhhNoooooooooo.....Mr Bill,
I've been running 20W-50W Synthetic in my 383 stroker......I hope I haven't caused damage using a heavy oil.... :confused: Should I switch to 30W......and be happy???? :confused:

467-Ratman

I had a straight 30 weight oil in my engine for break in, after about 500 miles I put in 20-50 Valvoline. My engine builder suggested the heaver oil for cam protection. Any thoughts on this would be appreciated :confused:

Wrecked82

I have been trying to eliminate, one by one, things that have been changed on the engine since it started running hotter.

1. Flushed (yeah, with CLR, but convinced that I did no damage - flushed with clear water for a long time). Was running hotter before flush anyway.
2. New water pump. Bearings making intermittent noise for months. Gave up about two weeks ago. Was running hotter before pump went out. No change with new pump.
3. Thermostat changed - new one made no difference. Robertshaw Extreme Performance 180 degree with two holes drilled. No change
4. Opened up both heater shut off valves and ran heater for awhile (in this Houston heat!) to make sure there was no cavitation in the intake manifold. No change.
5. Changed plug wires to Magnecor's. Now I know these are the best
:rolleyes: but I doubt they are so "hot" as to cause an engine temp increase. BTW, great wires.

What is happening is, after a long drive home in the heat, after about 15 miles or so, temp will begin climbing and stay near 210 until I hit the burbs, and then it will come down. The only event I can pinpoint is the oil change.

redwingvette

One reason heavier oils can be used for racing is that engine builders start with more clearence in the motor. Bearings for a stock motor recommend 0.0015"-0.0030" clearence while racing engines uses 0.004"-0.006"

Kingt

Larry, have you checked the fan clutch, and the foam sealing strips under the hood?

Wrecked82

Forgot to add that.

Clutch is very tight. When I stop the engine, fan stops within one turn or less. Then, very tight when turning by hand.

Foam seals are along side of radiator and side of hood over radiator. There is a full time air intake scoop in center of hood. I have blocked off the scoop with no change.

Have also cleaned radiator fins of all debris, bugs, paper, etc. etc. Sprayed with Simple Green and then hosed down to clean off any dirt.

Keep the ideas coming. Its there somewhere.

Radiator is a nice two core (joke). Maybe there is the problem. Don't remember problem last year. But then memory fades........

Wrecked82

Another one - replaced the catalytic converter. No change. Interesting thing, though. Catalytic converter was a Car Sound, which has two monolithic blocks. The rear block was missing totally. Only front block was in place. I remember months ago, I was having some problems with backfiring out the tailpipe. Must have destroyed the second block. :lol:

mountainmotor

Twinnie,it is the opposite. 5/30 oil is a 5 wt then as temp demands the VI improvers step in to thicken. The VI improvers are the weak link and take the hit in the hottest part of the engine/the ring area. In a mineral based oil a 10/30 uses the least of these. A straight wt uses zero

Delta. Your Synthetic is thinner by nature of it 's base oil. Compare the cold pour point to a mineral oil of the same grade.Also synthetic does not need as much VI improvers ,some use none at all.

Ratman,your builder bases his logic on hydrodynamic lubrication,what he does not know is that additives added to the thicker oil"or a 10/30" as a last line of defense,be it ZDDP,a Moly or some trick and exotic Esters such as Motul,or the new Mobil Supersyn which quite possibly is heat activated. These days a heavy springed valve train can protect a cam very well with a thinner oil,it is the additives that make or break a oil for this type protection.The new GF3 API classification"once again" has reduced some of the additives that protected our engines with heavy springs fine in the past. Some have substituted ZDDP with moly but still a bit of ZDDP "Zinc" present in the formulation.
I won't make a recommendation on which oil to use but will send you hunting for oils containing more than 1200 parts per million of Zinc. They can be found in Del Vac 1,Del Vac 1300, Chevron Delo400,Shell Rotella T and are diesel oils with the SL gasoline engine designation.There are other oils with a plentiful amout of Zinc as well,Pennzoil Long life and some others. Most of the over the counter SL oil contain beteen 700-900 PPM of zinc these days. I don't want that little bit protecting my cam. But there is a very good multi funtional additive available to turn a OTC oil like Pennzoil or other dino oil into somewhat of a super oil for lack of a better description.

The new process of hydocracking a mineral based oil has narrowed the gap between a dino and a synthetic. For example,the flash point of Pennzoil straight 30 wt is 450 F. The Del Vac 1300 is 446F and is a 15/40 that pours more like a 10wt when cold if one was to look at the spec sheet. These flash points pair up nicely to most synthetics. A synthetic is just a base oil,they use mineral based additives which will deplete over time. Almost forgot,that Del Vac 1,it is a synthetic for diesels,the only difference is the additive packages of the Diesel oils are more robust in that they have more detergents,anti corrosion adds ect ect.

In Synthetics their are Group IV which are PAO's,EOP's and POE's also a Group V which are the exotics. All are brutal on seals with out the addition of a seal swell agent of some sort

There are some high milaege oils out now that contain Esters to swell seals,but some have a Moly that is know to corrode metals,,I would thorughly check into these type oils befor using them for more than 3k intervals.

Discalaimer. All of the above is in my opinion,use your own judgement or call a oil manufacturer/follow owners manual ect on whatever oil you use in or out of your warranty period

Larry,retarded timing can cause over heating or a motor to run hotter,sincerely doubt the oil is your problem but lighter VI oil transfers heat better


:)





[Modified by mountainmotor, 6:09 PM 8/13/2002]

Twin_Turbo

That's what I said didn't I,. cold coiled up -> no effect on visc. warm -> uncoiled -> affect visc.

The polymer counteract thinning of the oil.

Marck


[Modified by Twinnie, 6:03 PM 8/13/2002]

mountainmotor

This is what I was referring to;

"When the oil gets hot they uncoil and becoime strands and do affect viscosity. This way the oil doesn't thin out too much"

It starts out thin,then thickens up.Thats the way the VI improvers work

Did not mean to take issue with this :)

Actually is you read a spec sheet'this Pennzoil for examle,others will be simaler" the VI index using the ASTM D-2270 of the 5/30 oil is 160 and the index of the 10/30 is 140

The High Temp shear is 3.1 for the 5/30 and 3.2 for the 10/30 with less VI improvers to burn away

Cold pour point on the 5/30 is -44F and the 10/30 is -33F thats cold!

IMO the 5/30's and the new 5/20's are for CAFE purposes and or EPA during cold starts

I do understand there are some fine 0/40s available now. Mobil can take a bow for that it seems !

Wish I could finish a post without getting kicked off line! Might try to post more tommorrow


[Modified by mountainmotor, 6:34 PM 8/13/2002]

Markm10431

have you taken temperature into acct? is it significantly hotter outside than before?

Wrecked82

[QUOTE]Larry,retarded timing can cause over heating or a motor to run hotter,sincerely doubt the oil is your problem but lighter VI oil transfers heat better...QUOTE]

Timing is set dead on at 6 degrees - at least it was two months ago. Might check it this weekend. Maybe move up a point or so and see.

JMV

Very interesting thread. This certainly causes me to re-think all I've been previously told about oils and proper weight selection, Thanks! :)