Any real harm in running SAE 30 during summer?

[Brian Barnhart]

With a positive displacement pump, flow will be the same regardless of oil viscosity unless the pump is bypassing. And oil viscosity has little, if any, affect on how fast things warm up. Warm-up time is chiefly dependent on starting temperatures and how far the pedal on the right is pushed.

 

[Eddie]

One point we may have overlooked is that not ALL lubricated parts in an engine are pressure lubricated. Time Chains, wrist pins and valve gear are examples. A lower viscosity oil get to these parts faster = better protection.

 

[BuickGN]

Originally Posted By: Eddie
One point we may have overlooked is that not ALL lubricated parts in an engine are pressure lubricated. Time Chains, wrist pins and valve gear are examples. A lower viscosity oil get to these parts faster = better protection.


If those parts aren't pressure lubed, how would a thinner oil get to them faster?

Either way, I'm not convinced you could tell the difference in time to full pressure/flow between a 20 and 30wt. What I do know is the 30wt will leave a thicker film on parts for protection at startup.

 

[Steve S]

Originally Posted By: Johnny
SpitfireS, that's an excellent point. If your running SAE 30 in your grocery getter the oil will never warm up, and we all know what that means.
Why wouldn't the oil get hot? Since the oil has to be moving so slow because it is so thick it has more time to pick up heat. "1 more dumb oil statement".

 

[XS650]

Originally Posted By: Steve S
Originally Posted By: Johnny
SpitfireS, that's an excellent point. If your running SAE 30 in your grocery getter the oil will never warm up, and we all know what that means.
Why wouldn't the oil get hot? Since the oil has to be moving so slow because it is so thick it has more time to pick up heat. "1 more dumb oil statement".


There's no shortage of those here. Do you have a total count?

 

[Audi Junkie]

I think I mistakenly reference Chevron SAE 30 PCMO, not Delo. Either way, it's the same as 15w-40 at cool/cold temps.

 

[Johnny]

Originally Posted By: XS650
Originally Posted By: Steve S
Originally Posted By: Johnny
SpitfireS, that's an excellent point. If your running SAE 30 in your grocery getter the oil will never warm up, and we all know what that means.
Why wouldn't the oil get hot? Since the oil has to be moving so slow because it is so thick it has more time to pick up heat. "1 more dumb oil statement".


There's no shortage of those here. Do you have a total count?

You two calling my statement dumb is like the pot calling the kettle black. You experts go ahead and run SAE30 in your late model cars and tell all your friends to do the same thing. Me and my dumb friends will continue to use 0w, 5W, and 10Wxxx oils.

 

[Jett Rink]

I can't pull a link out of my back pocket, but I think G-Man (or somebody) has some threads in here somewhere with him using a straight 30 in a Chrysler 300 in South Carolina. He seemed to be pretty satisfied with the results, if I remember right.

 

[jpr]

Perhaps somebody could explain what's confusing me - under what circumstances would the higher viscosity of a straight SAE30 at cold start be beneficial over the lower viscosity of a 5W30?

For comparison sakes, here's the Delo SAE30 numbers compared with Pennzoil Platinum Euro 5W30 at various temps:
100 degC = 212 degF Delo 12.1 / PP 12.1
40 degC = 104 degF Delo 105 / PP 67.1
20 degC = 68 degF Delo 346.1 / PP 127.6
10 degC = 50 degF Delo 726.5 / PP 277.9

It would seem like the net effect of running SAE30 would be to simulate cold start temperatures of about 10~20 degC lower than actual temperature. When would that be good thing?

 

[BennyL]

you guys are all nuts... i dont understand what the argument is essentially about? what benefit is there to running an SAE30 motor oil? the lack of VII's? why is that necessary? we all know that with the high quality of today's motor oil, a 5W-30 uses very little VII anyways, and the VII's of today don't break down and leave the kinds of deposits they once did back in the day.

so... WHAT IS THE BENEFIT? none, in my opinion.

to answer the question asked by the original poster: no. no harm. if you HAD to pour it in, you'll live. there's just not good reason to do so.

 

[Zaedock]

Originally Posted By: BennyL
you guys are all nuts... i dont understand what the argument is essentially about? what benefit is there to running an SAE30 motor oil?


I guess I'm nuts then, but I will tell you though, that my trail Jeep on a nice hot summer day, will turn 5 and 10W30 motor oils to water. I'll continue to use my SAE30 with no problems.

To answer the poster's original question: No, running SAE30 in summer will not harm your engine.

 

[SpitfireS]

Originally Posted By: Brian Barnhart
With a positive displacement pump, flow will be the same regardless of oil viscosity unless the pump is bypassing.

With industrial gear pumps I agree.
I've been looking up some data from gear pump manufacturers and the highest rpm I've found was up to 2000 rpm, and they call that "fast".
The Gerotor gear pumps that are used in most engines run at a much higher AND wider rev range, from 1500 rpm at idle to 9000-17000 rpm at redline.
In my opinon those pumps will pump less at higher revs and with thicker fluids @ lower revs, simply because the fluid (engine oil in this case) doesn't have the time to flow into the pump.
In other words: output is speed and viscosity dependant.

Commuting to work using the same road over and over again made it clear to me that with thinner oil the engine reaches "operating" temp faster, I say "operating" because I was looking at the water temp gauge.
Same season @ morning temps, same routine, same route, same driver, same car, same engine, different oil.

A single grade 30 weight oil may be just as thin (or thick) as a 5W-30 at 15C or 10C or even lower temps, at that point there would be no difference.
A 9,6 cSt 0W-30 will be much thinner at those temps, giving more oil flow through the engine (IMO) resulting in shorter oil warm-up time = less wear (according to the test results mentioned earlier in this post)

Pretty soon that 0W-30 will be changed and a UOA done.
Results will be posted.

 

[TallPaul]

Get Redline 10w30. Then you will have both a multigrade and a straight weight in the same oil. Then everybody can then be happy and stop bickering and stop calling other people's posts shiet or dumb.

Oh wait, no that won't work because then we'll all argue that Redline is shiet because of the bad looking UOAs ...

 

[JAG]

Originally Posted By: jpr
Perhaps somebody could explain what's confusing me - under what circumstances would the higher viscosity of a straight SAE30 at cold start be beneficial over the lower viscosity of a 5W30?
Maybe you didn't mean to phrase the question that way since of course nobody uses conventional straight weights for their inferior cold viscometric properties. These oils are used reasonably when this negative is not a large factor. The oil will have very high shear stability. Most conventional 5W-30 oils don't.

A straight weight synthetic offers much improved cold viscometrics than conventional straight weights. I haven't posted anything new here...oh well.

 

[Brian Barnhart]

Originally Posted By: SpitfireS
Commuting to work using the same road over and over again made it clear to me that with thinner oil the engine reaches "operating" temp faster, I say "operating" because I was looking at the water temp gauge.
Same season @ morning temps, same routine, same route, same driver, same car, same engine, different oil.

What oils were in use when you observed this?

 

[jpr]

Originally Posted By: JAG
Originally Posted By: jpr
Perhaps somebody could explain what's confusing me - under what circumstances would the higher viscosity of a straight SAE30 at cold start be beneficial over the lower viscosity of a 5W30?
Maybe you didn't mean to phrase the question that way since of course nobody uses conventional straight weights for their inferior cold viscometric properties. These oils are used reasonably when this negative is not a large factor. The oil will have very high shear stability. Most conventional 5W-30 oils don't.

A straight weight synthetic offers much improved cold viscometrics than conventional straight weights. I haven't posted anything new here...oh well.
Actually, that was exactly the point.

For the possible gain in sheer stability you end up accepting some significantly inferior cold start properties.

If you've got a race car with relatively fewer starts and relatively more time running flat out and consequently "needs" that sheer stability, then it's a good trade.

But for street car, if you didn't need that incremental gain in sheer stability in the winter, you're not going to need it in the summer either.

As for straight weight synthetics, most of them already seem to be double-billed as 10W30's.

 

[mechtech2]

If my original sane and safe advice is not considered informed enough, consider this:

No automobile Mfr. recommends a straight weight oil.
That should clearly tell anyone with an IQ over 75 something.
[And they didn't get their oil recommendations from plastic surgeons.]

 

[JAG]

Just want to point out that many 5W-30 and 10W-30 oils are just temporarily that. Same for 10W-40. Same for many synthetic 0W-40 and 5W-40 oils. Conventional 5W-20 oils use less VIIs than similar quality 5W-30 oils and are generally more shear stable. With an SAE 30, it doesn't lose significant viscosity unless diluted with fuel and water. If you want to match up the equivalent full operating temperature viscometrics of a multigrade vs a straight weight, you need to match up the HTHS viscosity of the multigrade's SHEARED HTHS with the straight weight's virgin HTHS...assuming little to no fuel and water dilution. With lower quality oils, a 10W-40 may be necessary to equate to an SAE 30. Then you'd have to compare the cold viscometrics between the SAE 30 and the sheared 10W-40. I personally have no use for a conventional straight weight oil.

Deposit control with VIIs is the other consideration. Again, nothing new here. Oh well.

 

[Pablo]

100 degC = 212 degF Delo 12.1 / PP 12.1/ ACD 10.5
40 degC = 104 degF Delo 105 / PP 67.1/ ACD 66.3
20 degC = 68 degF Delo 346.1 / PP 127.6/ ACD 176.4
10 degC = 50 degF Delo 726.5 / PP 277.9/ ACD 321.7

I went over a year on this oil in my 1996 Volvo 850 and the wear was phenomenal. Sure it was a good match for the engine, but my point being through the cold winter, there was no excess wear.

I would not do this with conventional SAE 30 in a cold climate. End of conversation.

 

[JAG]

Thanks for the ACD SAE 30/10W-30 data, Pablo. It's HTHS is 3.4 cP.
PP 5W-30's HTHS is 3.1 cP. It is a decently shear stable oil but it's HTHS could drop to 3.0 cP.

So, we have quite different oils here:
PP 5W-30: 3.0 to 3.1 cP HTHS
ACD:...... 3.4 cP HTHS