How much better is straight weight vs. multi?

[lars11]

There's a lot of talk and some guesswork about sae30 and that it is better than say 10w30 in air cooed ope.
Now I'd like some facts:
1. What's the working oil temp of a typical air cooled ope, say a briggs?
2. At that temp, what's the viscosity of a typical sae30, dino sae 10w30, synthetic 10w30 and say a 0w30? (Given that it is hotter than the standard 100C in there)
3. At that working temp, how much wors does the multi visc oils hold up to compared to the dino SAE30?

Come on, someone must have some numbers! I'm not interested in numbers like "watery" or "blackish", or other info like ZDDP. Just the viscosity and durability parts in this post.

I've been running ope's with everything from old 20w40 to 0w30 and have not had a real engine crash since 1981 when a 8hp briggs smoked and died on me. So I know they are not too picky, but this is BITOG so we want to know more, right?

 

[Clevy]

Straight grades don't shear like multi-grades and I don't think they have to adhere to the lessened zddp mandate as well.
If I lived in a hot climate that never saw freezing I'd likely run straight grades in my vehicles.
I just read an article about this very topic at the lubrication engineers site.
Interesting stuff.
Sorry op. I cannot help with temps and stuff I do look forward to the answers here.

 

[gfh77665]

Originally Posted By: Clevy
I just read an article about this very topic at the lubrication engineers site.
Interesting stuff.


Can you provide a link?

 

[Garak]

Originally Posted By: lars11
2. At that temp, what's the viscosity of a typical sae30, dino sae 10w30, synthetic 10w30 and say a 0w30? (Given that it is hotter than the standard 100C in there)

I suspect the HTHS would tell you more about the really high temperature characteristics.

 

[Coprolite]

Lars, I switched to running multigrade using the partial quarts left over from my auto fills. On the first change, I noticed a dramatic fuel economy jump. Keeping the air filter clean also helped conserve fuel. I have only anecdotal experience. I also haven't had an engine blow up or seize.

 

[stranger706]

Originally Posted By: lars11

1. What's the working oil temp of a typical air cooled ope, say a briggs?


A couple years ago I measured the oil temp in my Honda 160 lawnmower while I was mowing the lawn during the summer. Outside temp was 95F, sunny, and after 45 minutes of mowing the oil temp was only 190F. I use Pennzoil 4 stroke 30 weight.

I don't know why everyone assumes air cooled engines run hotter than other types. If they are designed correctly and the user is operating them correctly then they run the same temps as any other engine.

Even my dads air cooled 911 runs normal oil temps all year long. The only exception is track days.

 

[Gabe]

Originally Posted By: lars11
There's a lot of talk and some guesswork about sae30 and that it is better than say 10w30 in air cooed ope.
Now I'd like some facts:
1. What's the working oil temp of a typical air cooled ope, say a briggs?
2. At that temp, what's the viscosity of a typical sae30, dino sae 10w30, synthetic 10w30 and say a 0w30? (Given that it is hotter than the standard 100C in there)
3. At that working temp, how much wors does the multi visc oils hold up to compared to the dino SAE30?

Come on, someone must have some numbers! I'm not interested in numbers like "watery" or "blackish", or other info like ZDDP. Just the viscosity and durability parts in this post.

I've been running ope's with everything from old 20w40 to 0w30 and have not had a real engine crash since 1981 when a 8hp briggs smoked and died on me. So I know they are not too picky, but this is BITOG so we want to know more, right?


I believe that the API viscosity requirements of 10w30 supersede that of SAE30. So any 10w30 could be called straight 30.

The difference in viscosity for 30 wt oils depended on their manufacturer. You will have to look at the oil's pds and use the BITOG calculator to find the viscosity. The further from 40c or 100c, the less accurate the calculator becomes.

In high heat applications, generally speaking, oxidation is more of a concern than shearing. You should be looking at NOACK values.

A mower is not a high demand application; the plastic tank will melt before the motor oil breaks down.

 

[HerrStig]

Originally Posted By: stranger706
Originally Posted By: lars11

1. What's the working oil temp of a typical air cooled ope, say a briggs?


A couple years ago I measured the oil temp in my Honda 160 lawnmower while I was mowing the lawn during the summer. Outside temp was 95F, sunny, and after 45 minutes of mowing the oil temp was only 190F. I use Pennzoil 4 stroke 30 weight.

I don't know why everyone assumes air cooled engines run hotter than other types. If they are designed correctly and the user is operating them correctly then they run the same temps as any other engine.

Even my dads air cooled 911 runs normal oil temps all year long. The only exception is track days.

Some say the 911 engines are "oil cooled". To meet emissions standards they have to have a good temp regulation system. Insofar as oil goes, I ran my 8 hp L head Briggs genset for 23 hours nonstop using Rotella T6 and it didn't use a drop. Also started on one pull after sitting is 6 degree weather overnight. All info available from Briggs for the engine indicates 10 - 30 or 5-30. If 30 were better, I am sure they would have mentioned it.

 

[Blaze]

Originally Posted By: Clevy
Straight grades don't shear like multi-grades and I don't think they have to adhere to the lessened zddp mandate as well.
yep the straight 30 like Delo here is fairly high in zddp.

chromium-0
nickel-0
aluminum-3
copper-0
lead-0
tin-0
cadmium-0
silver-0
vanadium-0
silicon-4
sodium-2
potassium-2
titanium-0
moly-103
antimony-1
mang-0
lithium-0
boron-146
magnesium-13
calcium-3297
barium-0
phos-1379
zinc-1647
Vis-11.5
TBN-10.1
Oxidation-8
Nitration

 

[Doog]

I just use Rotella T5 10w30 in everything for my yard. One jug one stop shopping..$12/gallon...skip the rest. Easy wins again.

 

[Hokiefyd]

Originally Posted By: Doog
I just use Rotella T5 10w30 in everything for my yard. One jug one stop shopping..$12/gallon...skip the rest. Easy wins again.


Me as well. Too easy.

 

[Clevy]

Originally Posted By: gfh77665
Originally Posted By: Clevy
I just read an article about this very topic at the lubrication engineers site.
Interesting stuff.


Can you provide a link?


Nope. Sorry.Don't know how on my iPad. I'm sure it would be easy to find though using bing or google.

 

[TFB1]

On a 90* day, the old Briggs flat heads can run temps approaching 260-270F in the area of the valve cover on the side of the engine(near the exhaust)... Oil is exposed to this area...

I have one around here with 10w30 Syntec and another with whatever is handy(uses some oil)... My 5.5Hp Honda has a fill of 0W-40 Mobil 1...

 

[steve20]

About 5 years ago I measured the actual oil temp of an 8.5 Briggs vintage 1982 in a rear engine rider. I used it to collect leaves in the fall--temp was between 65-75 outside and the oil was 270 degrees. It worked much harder crunching and collecting leaves than mowing 4 inches of grass

 

[lars11]

Ok, good,now we are getting somewhere!
So that's 132 deg C.
Say that we know the visc for most oils at 40C, 100C and VI, then we should be able to figure out whether there is a big difference in viscosity between straight 30 HD and say 5w30 synthetics at 132C.
How to do this, anyone?
How do we compare effect on longevity at 132C for different oils?

 

[zpa]

I have an oil temp gauge hooked up on a Briggs flathead twin. At 20-25 C ambient the temps run 120-140 C depending on the loading. It seems that the flatheads run way hotter than OHVs.
Well you can always calculate the visc with a calc, like the one on this site if that's what you mean?
About longevity I would guess 130C is getting a bit too hot for a dino.