Amsoil 10w-40/AMO in 1997 Honda 650cc Magna

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Aug 2, 2002
Miles on engine - 15,000 Time on oil 3500 miles/1 yr - A 10 mile commute back and forth to work is main use. No oil consumption OEM air filter/Amsoil SMF oil filter Physical/Chemical Properties: Vis @ 100C, 10.5 Cst Oxidation, 18% of allowable Nitration, 28% of allowable TBN, 8.93 Fuel Dilution, 1.0% Wear Metals: Fe, 11 ppm Cr, 0 ppm Pb, 2 ppm Cu, 9 ppm Sn, 0 ppm Al, 19 ppm Silicon, 7 ppm Oil Additives: Mg, 59 ppm Ca, 3140 ppm P, 1262 ppm Zn, 1504 ppm Now running the Amsoil 10w-40/MCF for comparison.
TooSlick, The oil sheared significantly, barely a 30 wt after 3500 miles. This reaffirms my thoughts that oil in a motorcycle should be changed out at lesser mileage intervals... RevRider
I do not know if I agree. What did it start with? I know my bike oil (20-50) always thins but I did not care (based on oil tests). I am also running their new bike oil this year, then test again. So far, it (shifts) are softer and easier. Smoother is not something I would say.
750 Magna, perchance? No 650 of which I am aware. Yeah, the oil in a shared sump should not hang around too long. What I might start doing is to drain off about a litre or so of oil (by cracking the filter for a moment?) about half-way through the oil-change cycle and top off with a fifty-weight oil. That might be a good way to go. Thinking out loud here... John.
John, You're correct, its a 750CC. I'm not sure you can completely stop shearing in a wet clutch motorcycle application. To me the issue would be if the oil still provides adequate wear protection and shifting performance. Visually this stuff still looks like new oil on the dipstick and it's degraded very little chemically. This is a friends bike, so we're using it as a testbed. [Smile] TS
IVM, You can tell the MCF will be significantly more shear stable then the AMO product by comparing the ration of Vis @ 100C to HT/HS viscosity for each of these: AMO, 14.9/4.3 = 3.47 MCF, 13.9/4.5 = 3.09 Lower is better in this case.... This ratio tells you how "squeezable" the oil is and relates to polymer - VI modifier - content. All things being equal, an oil with more VI modifier will shear more in service. You can really see this by looking at the ratio for an SAE 0w-40: 14.4/3.6 = 4.0 Any oil with a ratio > 3.75 will shear badly in service - particularly in a high rpm, turbocharged application.
Hmmm, by that formula Red Line 10W-40 should be as shear stable as MCF (14.6 / 4.7 = 3.11). Now, if only the USPS would quit losing my used oil samples maybe I'd have some empirical evidence!
Blake, I'd agree about most of the RL formulations being very shear stable. Their VI's are fairly low, so you can tell they don't use much if any polymeric thickener. TS
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