Advantages of straight weight oil

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Originally Posted By: Zaedock
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.


Of course there is interest!

My guess would be your iron will be relatively normal and your aluminum will skyrocket if you run a 5w20. The two Jeep UOA's with a 20 grade that I've seen exhibited that trend.
 
Originally Posted By: edhackett
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


Like gear oil viscosities aren't comparable with engine oil? (Never understood why they do that, but I suppose there's no one to stop them.)

Thanks. That means the analogy is closer than I thought.

(But of course not the same, because its an analogy.)

(Sigh)
 
The aeros are started, and then usually run for a while, not a 2 minute jaunt down to the street.

The "advantages" of high VI don't play out in that sort of application...
 
Originally Posted By: Shannow
The aeros are started, and then usually run for a while, not a 2 minute jaunt down to the street.

The "advantages" of high VI don't play out in that sort of application...


I don't do 2 minute jaunts down the street. I have a bicycle.

(It takes straight weight oil too.)

But sure, in general, aero engines have a much less demanding role than car engines, but my original point was the alleged enhanced corrosion resistance of higher viscosity straight weight oils for (aero} engines that sit idle for long periods.

Whatever the design and operational differences, I'd have thought that sitting idle is going to be rather similar in a car and an aircraft engine.
 
Wandering around B+Q a while ago and noticed the following:-

OE/HDO-30 Lubricating oil, Internal Combustion Engine. Combat/Tactical Service MIL-PRF-2104E

Presumably thats a straight 30 weight oil. This was in the section that displays welding sundries and such, and I'd guess generators might spec a straight 30 oil.

I quite favor straight oils here, especially in a motorcycle, but have only used 40W (which might be rather high) because thats all I've found readily available. It wasn't expensive at 400NT a gallon, though it was only a little toy American gallon, so not as cheap as I at first thought.

Its not unusual in the UK for an oil to give its milspec on the label, but thats ALL this stuff had. Otherwise plain white plastic jerrycan, no brands/logos/pretty colours. Not B+Q's normal style at all.

Apparently made (or at least sold/packaged) by Chemical Specialist and Developments, Inc, Conroe TX 77305. I wondered if it might be fake, though you'd think B+Q would buy in enough bulk that they'd check supplier bonafides. There were a few typos on the label, but not beyond the usual run of industrial illiteracy. Health and safety stuff was a bit over the top, but that's not implausible for a US company.

Company website says they are mostly a defence contractor, (which fits) and not much else apart from "mission statements" and similar [censored].

Having checked it out a bit I went back a week or so later to get some for the "not summer", but it'd gone, and (of course) no one knew what I was talking about.

On the same shelf there were tins of Nyco Grease GN10. Looked it up. Its a general purpose AVIATION grease, made by a French company, and specified for extreme low temperature use (presumably at altitude).

I have no clue as to what it was doing on the shelf in B+Q in Taiwan.

Not important, but these little mysteries intrigue me. Stuff like this is why women find me such a fascinating conversationalist.
 
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Well I was going to do a run of SAE30 this summer. Now I've been transferred at I will suddenly be extreme short tripping my Jeep. Not thinking that's the scenario for a straight weight.

I dunno maybe it'd be better?
 
I don't even use it for them, I see no excessive consumption on M1 0W-30 so what's the point? Why make it any harder than it needs to be?

Originally Posted By: pavelow
Who uses straight weight oils in 2014? I can't see any use for them except for in lawnmowers and other small engines? lol
 
I used to use straight weights in lawn mowers but now even the little engines are all calling for 10w30.

Unless its for an old engine or an air compressor straight weights are obsolete.

A lot of the old timers run them in their boats but I don't see what advantage they offer over any of the modern 15w40's. Certainly not cost 15w40's are always cheaper.
 
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I could see a straight weight oil being best in an application where an engine was run continuously for long periods of time and not shut down and restarted very often at all.
Perhaps a generator of some sort?
 
Meh, I have an 8kW standby generator (Briggs twin) using 0W-30, and it runs now and then when the power fails. I really don't have to add any oil between changes which is usually twice a year.
 
Originally Posted By: zamadison
I could see a straight weight oil being best in an application where an engine was run continuously for long periods of time and not shut down and restarted very often at all.
Perhaps a generator of some sort?


I could see straight weight oils being best in an application where they never see low temperatures (due to climate or preheat), where the oil is subject to sheer (all applications, but especially motorcycles) where the alleged high startup wear (alleged because although I've seen the numbers quoted a lot, and they are plausible, I've never seen a source for them) is less of an issue due to the above, or due to the use of a prelube system, where the engine sits idle for long periods of time, or where the inferior (?) lubrication of polymeric viscosity modifiers is an issue.

Thats potentially A LOT of applications, but I don't know what the advantages (if any) are ACTUALLY, because I've seen hardly any evidence.

Either way, it's probably out there, but I havn't seen it. A lot of it is probably secret.

Someone on here recently (I thought it was in this thread, but I can't find it) posted a response along the lines of "or do you think multigrades are just a worthless marketing ploy" as if that was inconceivable.

I don't think they're just a marketing ploy, but "worthless marketing ploy" is, in a commercial context, a contradiction, like military intelligence.

If a marketing ploy is effective, it'll be anything but worthless to the people who implement it, regardless of any technical merit.
 
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