Advantages of straight weight oil

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I read an article online a while ago that suggested straight weight oil offered better corrosion protection to light aircraft engines (which sit idle for long periods) because it was retained on the parts better.

Failure rates were allegedly higher with multigrades.

Since my car sits idle for long periods, that'd be a reason to use it. Its got a mixture of CPC straight 40 and Delvac 15/40 in it at the moment, but summer is just around the corner.

Can't find the article now, unfortunately.
 
I ran the Delo SAE30 because I bought a butt load of it for $.99/gallon. If that deal didn't exist, I wouldn't purposely go out and buy a SAE30 when 5W30 is typically the same price and offers superior performance in most cases.
 
Originally Posted By: Ducked
Since my car sits idle for long periods, that'd be a reason to use it.


Not really. I doubt you run an air cooled, opposed, dry sump engine that burns leaded av gas.

My vehicles sit for extended periods outside and 5W30 has more than been up to the task, especially if your interval extends into the winter months.
 
I'm in Taiwan, but I have heard of these "winter months" of which you speak.

Re "5W30 has been more than up to the task" I could say straight 40 was more than up to the task in my Sierra, but you wouldn't know what, if anything, that meant, either.
 
Well PYB HD30 is available here at a bunch of locations, but I have yet to find a jug to keep the costs down. Napa does have it "on sale" for $3.59 a quart though I'd like to do better. Rotella SAE30 is available at Tractor Supply in jugs but I want to run PYB, it has been my favorite lube in the Jeep thus far.

I will look at Autozone.
 
Okay here's a related question. Why is the TBN on PYB HD30 about 7 when the TBN on PYB 5w30 is almost 10? According to Pennzoil the HD30 still has detergents and anti wear additives, it even has the "removes up to 40% of sludge on the first change" advertising stuff on it.
 
Originally Posted By: dlundblad
In the summer heat at least, I wonder if it would be beneficial to buy PYB HD 30 weight to use as that 6th quart or as a top off oil.


I have done that for years. I always felt it would combat the shearing that naturally occurs.
 
I figure part of being a part of this forum is a willing to experiment.
smile.gif
 
Originally Posted By: Zaedock
Originally Posted By: Ducked
Since my car sits idle for long periods, that'd be a reason to use it.


Not really. I doubt you run an air cooled, opposed, dry sump engine that burns leaded av gas.



True, though I'm not sure how those factors affect the analogy, if at all.

The difference in the oils is perhaps more relevant.

As I understand it (I havn't researched this and could easily be wrong) straight aviation lubricants for piston engines are typically of higher viscosity (eg Aeroshell range goes from 65 to 120) and non-(metallic)-detergent. These properties might reduce drain-down and increase corrosion protection relative to the automotive equivalents.
 
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Originally Posted By: Red91
I figure part of being a part of this forum is a willing to experiment.
smile.gif



This place is terrible for that I can't get in all the fiddling I want to do, it's the BITOG curse. Leaning hard towards a run of PYB HD30 for curiosity's sake though.
 
Fiddling is cool. Having done the SAE30 thing, I'll be fartn' around with 5W20 in my Jeep 2.5L powered buggy this summer. I may do a build thread if there is interest.
 
Originally Posted By: Ducked
Originally Posted By: Zaedock
Originally Posted By: Ducked
Since my car sits idle for long periods, that'd be a reason to use it.


Not really. I doubt you run an air cooled, opposed, dry sump engine that burns leaded av gas.



True, though I'm not sure how those factors affect the analogy, if at all.

The difference in the oils is perhaps more relevant.

As I understand it (I havn't researched this and could easily be wrong) straight aviation lubricants for piston engines are typically of higher viscosity (eg Aeroshell range goes from 65 to 120) and non-(metallic)-detergent. These properties might reduce drain-down and increase corrosion protection relative to the automotive equivalents.


*sigh* - the analogy is that your application is completely different and not comparable to your vehicle use or the type of fuel it burns (oil is contaminated by combustion byproducts).

I have been working on engines for over 20 years. I have completed engine replacement with both rebuilt and used units. In the extreme cases, I have pulled apart engines that sat on a shelf for a decade and the inside was coated with oil. You are looking for a "protection" that is not needed. Run the recommended viscosity and enjoy your vehicle.
 
Originally Posted By: Ducked
hed this and could easily be wrong) straight aviation lubricants for piston engines are typically of higher viscosity (eg Aeroshell range goes from 65 to 120) and non-(metallic)-detergent. These properties might reduce drain-down and increase corrosion protection relative to the automotive equivalents.


Aviation single grade oil viscosity is on a different scale than SAE automotive oils. Divide by 2 to get the equivalent SAE viscosity. 100 = SAE 50. The multi-grades are on the SAE scale.

Ed
 
Originally Posted By: Red91
Would anyone here actually try a fill of monograde in an application where it's tolerated? Just for kicks.


I've tried SAE30 in several vehicles just for kicks. Mind you, I should qualify that. I used Amsoil's fully synthetic ACD SAE30, which by nature of it's synthetic base stocks, can qualify for 10W30's cold temp pumpability. So essentially, it can be considered a VII-free, synthetic 10W30 oil that is properly categorized as an SAE30.

My impressions vs. the typical syn 0W30 or syn 5W30 that I've normally used prior to that in the particular vehicles in question... I noticed no difference whatsoever in driveability. Summer cold starts were identical as expected, and winter cold starts had a very very slightly slower cranking speed compared to the usual 0W30 (again, to be expected). No funny noises. Quiet and smooth engine running. Was looking to identify any wear metal changes in UOA, but I don't think it made any difference in that regard.

So in short, after many runs in different vehicles, I haven't felt the need to run it again. I'm not sure if there would have been long term benefits or detriments of using it. Even in my lawn and garden equipment I usually use 5W30 syn and call it a day (especially for the genset and snow blower that will be started in very cold weather - I'm not concerned about the lawnmower so much).
 
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