oil weights?

So I have read and been told that all motors benefit from newer oil. Meaning that I can safely use lower weight oils such as 5w30, 0w30 in my 20 year 3sgte which came from the factory with a recommended 10w30 or 10w40 oil rate.

Recently a friend purchased a big block chevy for a project. The engine was apparently built by the previous owner. The po stated that he used some reaallly high viscosity oil, something like 20w40 for the engine.

So what is the reality behind oil? are high weights really needed for high output engine? Or are they just needed for extreme temperatures?

"It depends!"

Modern engine with coated bearings and pistons and light-tension everything and stiff cranks and stiffer blocks that allow sub-.001" bearing clearances... Use the thin stuff!

Old stuff with bearing clearances you can stick a paperclip through because the block moves around a lot and the crankshaft is a noodle and the valvetrain is really heavy so the valvesprings are stiff so the cam flops around a lot too - Use the thick stuff!

What I'm getting at is, high viscosity oil is kind of a crutch for high bearing clearances required when using floppy noodly components.

Use what the factory recommended. As stated what weight oil you need is dependent on how the engine is built. In your case it can also mean how worn it is. As an engine get older and worn the oil pressure goes down and using heavier weight oil can help maintain normal oil pressure.

But on an old engine with loose tolerances, what good does high oil pressure do? High pressure does not equal high flow, and the tolerances are loose no matter what weight oil or pressure measurement you have. The same way a high-volume oil pump won't compensate for worn bearings, thick oil won't help either. It does make the gauge register higher, though, which evidently means the engine is healthier.

smog7 wrote: Recently a friend purchased a big block chevy for a project. The engine was apparently built by the previous owner. The po stated that he used some reaallly high viscosity oil, something like 20w40 for the engine.

I'd be a little concerned.

Sounds too much like cavemen "bigger is better, thicker is quicker" thinking. I'd question his overall building prowess.

I can't think of a good reason to use thick oil on a new rebuild. Maybe diesel.

smog7 wrote: So I have read and been told that all motors benefit from newer oil. Meaning that I can safely use lower weight oils such as 5w30, 0w30 in my 20 year 3sgte which came from the factory with a recommended 10w30 or 10w40 oil rate.

New doesn't mean thin, new means new formulations, additives, tests, etc.

Like the newer oils that produce less ash when they burn- has nothing to do with oil weight, but all to do about formulation.

Eric

Knurled wrote: "It depends!" Modern engine with coated bearings and pistons and light-tension everything and stiff cranks and stiffer blocks that allow sub-.001" bearing clearances... Use the thin stuff! Old stuff with bearing clearances you can stick a paperclip through because the block moves around a lot and the crankshaft is a noodle and the valvetrain is really heavy so the valvesprings are stiff so the cam flops around a lot too - Use the thick stuff! What I'm getting at is, high viscosity oil is kind of a crutch for high bearing clearances required when using floppy noodly components.

This is a bit of a misnomer...

SBC 350 bearing to journal clearance: 0.0008-0.002

S2000 FC20 bearing to journal clearance: 0.0007-0.0016

The clearances are really not all that different from a "state of the art" zingy engine built by Honda and an ancient 50's design luggy engine made by GM.

In reply to Knurled:

You said "floppy noodle"

I think it bears mentioning that a big factor in the manufacturers' recommendation for oil weight is EPA fuel efficiency. They are looking to squeeze out the last fraction of an mpg and they are quite happy to sacrifice the life of your engine to get there, full well knowing that they will likely get out of the warranty period without your engine taking a E36 M3.

1988RedT2 wrote: I think it bears mentioning that a big factor in the manufacturers' recommendation for oil weight is EPA fuel efficiency. They are looking to squeeze out the last fraction of an mpg and they are quite happy to sacrifice the life of your engine to get there, full well knowing that they will likely get out of the warranty period without your engine taking a E36 M3.

It bears in mind mentioning, too, that manufacturers test the bejesus out of engines to make sure they survive. Nothing like bad internet words to hurt a company. Even for cars out of warranty. Resale value has a strong bearing on sales strength.

Again- new oil is NOT thin oil. If your car was designed for 20w50, I would not go much more than 10W40 thinner. New oil spec is for what is in the oil, not the viscosity.

The "hot" oil viscosity has not changed much over the years. '50's cars used 30wt oil in the summer and 10 wt oil in the winter. Multiple viscosities took care of that. 10W(inter)-30 for example. My new Fiesta says to use 5W-20. Thinner oil flows quicker.

It would be very naive to think that politics doesn't play a major role in the manufacturers' recommendations. We've been over this subject before, people! Manufacturers don't care about the experience of the third or fourth owner of a car with 200,000 miles on it. They care about the ownership experience of the guy that plunked down the cashola for a new vehicle.

Some good reading here: http://www.machinerylubrication.com/Read/518/motor-oils

The strategy of the mfrs is to have you run the low-viscosity stuff through the warranty period, then wean your motor over to "high-mileage" oil after your motor is clapped out and you're ready for a new car.

1988RedT2 wrote: It would be very naive to think that politics doesn't play a major role in the manufacturers' recommendations. We've been over this subject before, people! Manufacturers don't care about the experience of the third or fourth owner of a car with 200,000 miles on it. They care about the ownership experience of the guy that plunked down the cashola for a new vehicle. Some good reading here: http://www.machinerylubrication.com/Read/518/motor-oils The strategy of the mfrs is to have you run the low-viscosity stuff through the warranty period, then wean your motor over to "high-mileage" oil after your motor is clapped out and you're ready for a new car.

I think it's very naive to always think that manufacturers are out to get you.

Yes, #1 priority is the guy who pays the money for the new one.

But if you ignore re-sale value, then you are killing yourself via discounts and after lease prices. That's well noted now, moreso that emissions warantees are pushing out to 150k miles. Way beyond normal #1 driver, and pushing to the 3rd owner.

If you don't want to belive that engines are tested WAAAAY beyond what you would normally run, that's your issue. More often than not- high mileage issues are due to PO's who don't change oil on a regular basis. Even then, they will do pretty darned well.

edit- IMHO, that's not a very good read. It tells you what "common sense" is, which isn't exactly correct.

Another link for all to look at: http://www.bobistheoilguy.com/cms/index.php

One other thing to be worried about with "new" oil in "old" engines is the lack of zinc in new gas engine oils causing excess wear on flat tappet cams. There's differing opinions but lots of anectdotal evidence out there on the web that this is a real problem to be worried about. I put a diesel oil into my 951 for that concern, and will go with Brad Penn oil for my next change.

tuna55 wrote: SBC 350 bearing to journal clearance: 0.0008-0.002 S2000 FC20 bearing to journal clearance: 0.0007-0.0016 The clearances are really not all that different from a "state of the art" zingy engine built by Honda and an ancient 50's design luggy engine made by GM.

And if you'll note, SBCs didn't require 20W50 back then either.

Racing tolerances were sometimes in the .005" range...

pigeon wrote: One other thing to be worried about with "new" oil in "old" engines is the lack of zinc in new gas engine oils causing excess wear on flat tappet cams.

The chemical compound starts with "zinc" but it's the phosphate that does the cushioning. (I forget the chemical name... zinc dithio-something-phosphate. ZDDP)

Kinda like nitrous oxide... it's not the nitrogen, it's the oxygen!

When we do oil changes on the older vehicles, we use Brad Penn or add a bottle of GM engine oil supplement.

iceracer wrote: My new Fiesta says to use 5W-20.

Ford started using 5W-20 in 2001 one for CAFE reasons.

The sticker under the hood of my 2000 Ranger 3.0 says 5W-30, but current specs say 5W-20.

Amsoil has quite a lot to say about it.
http://www.oilsandlube.com/5w20_oil_facts.htm

In reply to alfadriver:

Just because you're not paranoid doesn't mean that they're not out to get you!

But seriously, I'm not paranoid. I'm just not fool enough to believe that the manufacturer's recommendation is primarily aimed at ensuring that I am satisfied with my vehicle. I'm certainly not the only one who knows that meeting CAFE standards is the primary driver behind the 5W20 recommendation.

I have no doubt that regular changes of 5W20 will get me through the warranty period and beyond. But is it the BEST oil for my engine? I sincerely doubt it.

Knurled wrote:

tuna55 wrote: SBC 350 bearing to journal clearance: 0.0008-0.002 S2000 FC20 bearing to journal clearance: 0.0007-0.0016 The clearances are really not all that different from a "state of the art" zingy engine built by Honda and an ancient 50's design luggy engine made by GM.

And if you'll note, SBCs didn't require 20W50 back then either. Racing tolerances were sometimes in the .005" range...

I think you missed the point. I meant that it isn't as if all old engines had huge bearing clearances. That is not the driving factor when it comes to oil weights as judges by those two polar opposite examples.

1988RedT2 wrote: In reply to alfadriver: Just because you're not paranoid doesn't mean that they're not out to get you! But seriously, I'm not paranoid. I'm just not fool enough to believe that the manufacturer's recommendation is primarily aimed at ensuring that I am satisfied with my vehicle. I'm certainly not the only one who knows that meeting CAFE standards is the primary driver behind the 5W20 recommendation. I have no doubt that regular changes of 5W20 will get me through the warranty period and beyond. But is it the BEST oil for my engine? I sincerely doubt it.

You do know what alfa does for a living and where he works don't you?

1988RedT2 wrote: In reply to alfadriver: Just because you're not paranoid doesn't mean that they're not out to get you! But seriously, I'm not paranoid. I'm just not fool enough to believe that the manufacturer's recommendation is primarily aimed at ensuring that I am satisfied with my vehicle. I'm certainly not the only one who knows that meeting CAFE standards is the primary driver behind the 5W20 recommendation. I have no doubt that regular changes of 5W20 will get me through the warranty period and beyond. But is it the BEST oil for my engine? I sincerely doubt it.

So, where did you go to specialize in tribology? To say that YOU know better than the engineers that I work with is a pretty bold statement.

Oh, and I'd love to see data where people who changed their engine oil regularly- ON schedule- had any increase in engine failures within 50k miles or 5 years of the warantee ending that were engine oil related. I see it as an urban legend.

Lots of people think they know what's best for their car. Few people actually know, as far as I can tell.

alfadriver wrote: So, where did you go to specialize in tribology? To say that YOU know better than the engineers that I work with is a pretty bold statement. Oh, and I'd love to see data where people who changed their engine oil regularly- ON schedule- had any increase in engine failures within 50k miles or 5 years of the warantee ending that were engine oil related. I see it as an urban legend. Lots of people *think* they know what's best for their car. Few people actually know, as far as I can tell.

I'm no stranger to bold statements.

Speaking of which, I would like to hear you say that 5W20 is THE BEST oil for my 2005 Duratec, and that the manufacturer's decision to recommend that weight oil was in no way influenced by politics, i.e. the CAFE standards.

Now THAT would be a bold statement.

z31maniac wrote: You do know what alfa does for a living and where he works don't you?

Ummmm. Nope? But I'm starting to get a little info in that regard. I'm sorry, is his bio posted somewhere around here?

Ok, the oil that Ford specified for the 2005 Duratec IS the best oil for your engine.

Even put it in bold, how's that? Being that I don't have your owners manual in front of me, I don't know the correct weight.

Who cares if it's about CAFE- how many posts here are about us (the entire industry) ignoring fuel economy- so here's one that keeps it in mind, and now it's bad all of a sudden?

BTW, thicker oil will be a problem in colder temps. Just sayin. (pressure does not always mean more flow- usually means less)

Still- where did you specialize in tribology?