Honda 18hp Tractor, Schaeffer 15W40

[Bror Jace]

Engine Make: 1996 Honda (4518H Tractor)
Engine Model: GX640 OHC 2-cyl, 38.7CID, Liquid cooled
Fuel Type: Gasoline
Oil Type: Schaeffer S7K synth. blend 15W40
Hours On Oil: Approx. 60-70 hours
Total Engine Hours: Approximately 500
Make -Up Oil: 0 quarts
Air Filter: factory
Oil Filter: Castrol MaxPro #3593A
Oil Capacity: 2.5 quarts

Initial Remarks: This is the first sample of used oil taken from this 18hp, liquid-cooled tractor engine which I’m having tested. Oil was in use for a total of about 13 months. This is the first time I’ve used a combination gas/diesel oil in this engine. Prior fills have been synthetic (Mobil 1) and or a mixture of synthetic and a conventional oil. The machine sees typical lawn & garden duty: 2-3 hours of mowing each week from May to October with some additional hauling of yard waste and occasional other uses. Tractor operates in very sandy conditions necessitating cleaning of the air filter’s foam pre-cleaner 2-3 times per year. We experienced some drivability problems with the tractor this year causing me to replace the (original) fuel filter which appeared clogged with dirt & debris. Old gasoline (possibly moisture contaminated) may have also contributed to the engine’s stumbling, uneven performance.

Aluminum 3
Chromium 1
Iron 10
Copper 4
Lead 1
Tin 0
Molybdenum 101
Nickel 0
Manganese 0
Silver 0
Titanium 0
Potassium 0
Boron 11
Silicon 5
Sodium 4
Calcium 2601
Magnesium 76
Phosphorus 908
Zinc 1200
Barium 30

Sus Viscosity @ 210F: 370F (should be 370F or greater)
Fuel Percent: less than 1% (should be less than 1%)
Antifreeze: 0%
Water: 0%
Insolubles: less than 0.2% (should be less than 0.5%)
TBN 7.8

 

[Bror Jace]

Blackstone comments: "Bror, we have no averages for this type engine and though we could set you up with average metals from something comparable, would rather just tell you that wear metals this low and in this balance would be perfectly normal for any type gas engine we are familiar with. Air and oil filtration are okay. No gas or moisture found. The additives in this oil most closely resemble Motorcraft 15W40, though this oil has a molybdenum (anti-wear) additive. This oil is working well for your engine, especially in the lower end. The TBN was 7.8, plenty strong yet."

Bror's comments: Well, as you can imagine, I'm pretty pleased with these results. I was hoping that the iron would be a bit lower (keep in mind, this is a fairly small motor with a 2.5qt sump) but I have to keep in mind that this tractor has been in use about 7 years and has had approximately 5 oil & filter changes in that time ... not quite once each year. The oil was usually a backyard blend of Mobil 1 (Tri-Syn only) and some mineral oil. Weights used ranged from 10W30 to 20W50. I don't believe I ever used a dual gas/diesel in this before so the potent detergent package in the Schaeffer 15W40 might have scavenged a few PPMs here 'n there. Also, the depleted moly (VOA is ~200PPM) indicates that some metal-to-metal contact was occurring. All this suggests that a next result would be even better if I decide to test a sample again next year.

I'm all but flabbergasted that the air filtration got great marks. It does have a good-sized paper element (4" v 6" square) with a sheet of oiled foam as a pre-cleaner. This sheet of foam gets pretty nasty-looking after just a couple months of use (mowing) and this particular element has been in use at least 4 years. I have a replacement ... but don't know when I'm gonna install it. Maybe at the end of next year?

The spin-on oil filter which came off this thing was a Castrol MaxPro #1334 ... the less expensive WIX line. It's the same filter which fits on a lot of older Honda cars including my old Civic Coupe. They are compact (important in this application), the baseplate had massive, free-flowing holes in it and the whole unit is built like it was meant to be a highly durable component, not a throw-away piece. When K-mart was selling these and their slightly more expensive brothers (with denser media), I should have bought an armload. As it is, I am out of these and for a replacement, I put on a SuperTech. Overall construction quality doesn't seem near as good and its larger size is NOT a plus in such cramped quarters. Oh well, it'll probably do okay.

--- Bror Jace

 

[darrenc]

Wow! Those are better results than many of the UOA we see for cars with 3000 miles.

 

[MolaKule]

Bror,

Excellent showing for 13 month duty. I would only expect these results for half of that period.

 

[Terry]

Bror, whats the SUS Vis ?

TD

 

[Bror Jace]

Yeah guys, I should be pretty happy with that. Some of that iron is inevitable with a 13 month interval. I'm really impressed by the lead (1) and fairly low silicon (5).

Terry, Oops! The SUS Visc was 65.9 and Blackstone's range is 65-76. The chart I have shows a 40 weight range to be 68.3 - 83.11. What gives?

You would have been interpreting results from a sample of Schaeffer 5W30 out of my Nissan 2.5L engine in another month but during a recall service, the dealership dumped it.

We'll have to wait until the spring when you'll be seeing a sample of Red Line 5W30 from the same motor.

--- Bror Jace

 

[Terry]

I look forward to the RL sample and sorry to hear the 7000 blend was dumped.


My charts and thats what I use, show SAE 40w= 70-85 SUS @ 212 F.

Design range for this oil is 14 to 16 cSt@100C or the upper end of the range above. 65.9 is SAE 30w range.

I think fuel dilution may be a issue here and your comments confirm that with the fuel filter and dusty air filter problems.

Intermittant fuel dilution will not always show in the fuels testing if the event occured well before sampling then was cooked out afterwards.


That added to the iron bump too.

TD

 

[Bror Jace]

Thanks for the insight, I was thinking that the fuel might have been higher at certain times during this interval. Not sure how flash-off works, exactly. I'm sure it is different in each application but I have no 'feel' for how long it takes. One 2-hour interval? Several strung together in a row?

In any event, when I got things sorted out, this machine ran fine.

So, this oil sheared a bit? I'll have to see if I can find a VOA on this site for comparison. I wouldn't be surprised to see a bit of shearing as this was a relatively long interval and this engine seems to run very hot despite being liquid cooled.

When Dad runs this tractor, he tries to mow the entire yard (a couple acres of grass - 2.5+ hours) in one shot and does not stop to remove the clippings from the radiator at the halfway point as I do. It is not unheard of for him to set off the high-temp alarm this machine has when he does this ... especially on warmer days.

I'm also pleased that the headgasket appears to be sealing well.

--- Bror Jace

 

[JohnBrowning]

Bror most would be happy with this report with much less time in the crank case in a car. Lawn and garden equipment usualy throws much higher wear metals then this. I can not wait to see how it sorts out since the rough running and fuel issue have been resolved!!

 

[Bror Jace]

I don't know JB, I don't think I'll bother testing a sample from this engine again. I was worried about the TBN in an engine which is run only seasonally and then sits for a great deal of time.

But this UOA shows me that this oil, changed yearly, will do fine. Heck, I probably could leave the filter on and change it out only every other year as the manual states. But, I know that the dirtiest oil is in the filter so I might as well swap that out as well ... do a proper job.

--- Bror Jace

 

[Bror Jace]

I just thought I'd bump this up ... no particular reason.

--- Bror Jace

 

[TooSlick]

Think of this as a small, high rpm motorcycle engine and you'll understand why it sheared. Any lubricant with polymeric thickeners will shear in this situation. Of course, since this engine specs 10w-30, the thinning was of no concern.

If there was any scavanging going on, you'd see elevated lead. That's the metal that seems to become incapsulated by sludge/varnish deposits. This looks like very clean engine going in. The low level of insolubles would indicate very little fuel contamination, based on the small sump and the # of hours on this sample.

You could just change filters and probably run 125 hours on the same fluid. The presence of a FF filter makes a dramatic difference in this type of application.

 

[MolaKule]

As a rough estimate, figure 150 miles/engine hour (larger engines) to 300 miles/engine hour (smaller engines) and you'll see that this oil has suffered an equivalent 9750 miles minimum.

Iron wear is really low for this hourage and this oil must have a good metal deactivator additive since copper is very low.

This oil viscosity and additive package does well in this engine.

 

[Brett Miller]

That engine will go 2000 hours easily with that kind of wear.