Hot vs Cold Oil Change (test results provided)

[M.D. Holloway]

Over on the tech bored, the topic of oil change and if it is better to change hot vs cold has been discussed. I always wondered if the oil that was cold was any differnt than the hot oil (save the temp & viscosity). I tested both hot and cold to see if prehaps the hot oil stirred things up more and kept it in suspenion better. Not a true study based on statistical methods but never the less it was interesting. Both oils look pretty darn close. So close that I would say that oil smapling can be done hot or cold.

Draining is another story. Drianing cold will take much much longer. If you have nothing better to do and you don't like hot oil dripping down you arm, cold changes may be fine.

Personally, I like hot oil dripping on me so I get it rip snorting hot and stick as much of my arms under the blazing stream as I can! J/K

Here are the oil analysis results on my 96 Volvo. I did change the oil because the oxidation/sulfation/nitration was getting high. but interestingly enough, the TBN was still pretty good. Mind you, there is 48,000 on this oil.

[kach22i]

There is a thermostat that opens when the oil is hot enough to send oil to the front oil cooler or trombone oil cooler. If this valve is closed you will get about two less quarts of oil than with a hot oil change.

This is all you need to know.

I am not an expert, just been around you guys long enough and done a few oil changes each way.

Edit: Is the bottom sample done hot? It has more Zinc in it for sure.

[M.D. Holloway]

The bottom sample was cold. The level is within experiemental error for the instrument that is used (<5%). The Zinc is found in a common anti-wear agent. It I was to pontificate and speculate, I would say that the hot oil allows the Zinc to plate on the metal surface and when cold and has a decreased affinity. Sounds cool but I do not think it is accurate.

[singpilot]

Mike;

I have several (LOL) air and water cooled bikes. Wet clutches mostly. So that means the motorcycle oil, SG I think. I have been using the Valvoline 4 stroke stuff 20-50. It is reasonably priced in quantity to make early changes (2K miles) easy.

I have often wondered about the cold change. After the drain is down to a drop or so, I usually pour half a quart in with the drain open to 'flush' the remains out of the pan, and it seems to work; there is half a quart or so of black stuff comes out before the new oil drains, hot or cold. I always drop the filter first, in case the check valve was to allow the old oil to drain back. All of my filters (except for the beemers) are wrapped with the magnetic band.

There are times I cannot run the bike to warm it up, and figured by leaving it to drain for a long time, and tilting the engine to get it all out, along with the above, I had to 'be there' compared to the warm oil change.

How much does the oil analysis cost, and would the layman be able to interpret the results?

[M.D. Holloway]

Sing - motocycle oil is unique due to the clutch. The oil actually has to maintain a certian "grippyness" (thats the technical term). Actually the technology is somewhat similar to ATF fluid in that the balence between the co eff of friction v. the co eff of lubricity have to have a certain balence and if you upset that balence than you can feel it when you shift. Eventually you will get premature clutch wear if the oil is sub-par. The fact that you are getting a black sunstance at the bottom of the pan is troubling. That is sludge for sure. There are a few resons why they develop:
Inferior Base Oil - When the base oil contains one or more of the following; light fractions, sulfur, low molecular weight hydrocarbons.

Insufficient Concentration of Performance Additives- Low concentrations of anti-wear agents and/or friction modifiers produce wear metals and localized frictional heat. Low concentrations of demulsifiers can lead to emulsified oil, which hastens oil oxidation.

Yellow Metals (copper, brass, bronze) - Contaminants from external or internal sources can catalyze oil oxidation and lead to deposits and additive depletion.

Heat - High ambient temperatures, operational heat (from kinetic energy or combustion), frictional heat (from metal to metal contact), pressure (from aeration and/or operation) can accelerate oil oxidation and additive depletion.

Water - By-products of combustion and/or external contaminants can hasten oil oxidation and lead to deposits, additive depletion.

Acids - Develops when base oil breaks down into reactive species, produces sludge, varnish and/or other deposits, or external source such as acid washing. Common forms are sulfuric acid, nitric acid and various carboxylic acids.

Caustics and Solvents External Contamination - breaks the oil molecule into reactive species. The reactive species may polymerize to form resinous deposits.

It is rather interesting how sludge forms. Found in oil pans, sumps, housings, reservoirs, and bearings. The formation begins when contaminants begin to settle out of the oil. Sludge develops with excessive accumulation of contaminants leading to additive depletion and oxidation. Sludge is composed of water, carbon residue, oxidized oil, and acidic compounds which can lead to further oil decomposition. It can restrict oil flow leading to increase system pressure, temperature, wear, and oil viscosity increase. Not a good thing.

I can get you oil analysis through a great lab (which I have nothing to do with) for about $15 a test. If you get 10+ tests I think I can get it down to $10 each. If your interested, let me know.

I should get Wayne to offer these through Pelican.

[M.D. Holloway]

Oh ya, as far as being able to understand the results? No problem. I can send you a handbook I wrote the will have you understanding this stuff in 20 minutes!

[singpilot]

Mike;

Wayne SHOULD offer these.

I don't have sludge in the drained oil, I meant simply that I can get a little more old (darker) oil out by the 'flush' method.

The Beemers use a dry clutch, so regular synth oil goes in those.

I suspect that many bike owners are not aware of the requirement for the special oil. The same oil that runs in the trannys. I think I read somewhere that the gearbox shear in the meshing does as much damage to the oil as the engine does.

Thanks for the info!

[Joeaksa]

Michael,

Any airport mechanic has outlets for doing oil samples, we do them on almost every 100 hour or annual. Ask around your area, BUR or VNY and the DOM where you are flying.

Lube, 48k on this oil??!! What kind of oil are you using and assume that you were changing filters often? Have used syn oil when living in Europe but changed it at 15k or so.

Joe A

[M.D. Holloway]

Joe,
I'm using Certified Labs STRATA XL. It is a straight mineral based oil! I changed it to STRATA XTREME which is a blend. I expect that to last even longer! No, I didn't change the filter because the contaminants were kept in check. They can either come from internal sources or external sources. Interally the deposit formation is held in check with good chemistry, externally I changed my air filter twice and very good about not contaminating my sampling port which is my dip stick tube.

[ZLP]

Originally posted by kach22i
There is a thermostat that opens when the oil is hot enough to send oil to the front oil cooler or trombone oil cooler. If this valve is closed you will get about two less quarts of oil than with a hot oil change.

Edit: Is the bottom sample done hot? It has more Zinc in it for sure.

Not if you have Elephant Racing finned lines.