Here's a link that shows the test results that Skip (pococj) got from an oil test comparing different oils ... HERE

Skip also said... "when I had several oils tested the Mobil 1 15w-50 car oil had less moly than the V-Twin version, and the HD Syn 3 had virtually no moly. Both of the M1 oils had more anti-wear additives than the HD Syn 3 stuff. And the M1 oils are true synthetics, while the HD stuff is hydro cracked.


With an explination of the different values shown below...

Got the results today. Pretty interesting if you're into this stuff. Here's a bit of a primer to explain what the different elements are for, and then the results. Since this forum's format doesn't seem to support tables, the results will be a bit difficult to read. I will e-mail the results as an attachment to anyone who e-mails me asking for them (pococj@aol.com). The attachment will be in Adobe PDF format. All values are ppm.

Anti-corrosion: Boron, sodium, zinc

Acid neutralizer, cleaning, & dispersants: Magnesium, calcium, boron (acid neutralizer)

Anti-foam: Silicon

Anti-wear: Phosphorus, zinc, molybdenum (friction modifier)


Mobil 1 15w-50 Extended Performance (replacement for "red cap) car oil

Si - 2 Na - 8 Mo - 79 Bo - 281 Ca - 2937 Mg - 17 P - 1223 Zn - 1376


Mobil 1 V-Twin 20w-50

Si - 4 Na - 9 Mo - 91 Bo - 255 Ca - 2648 Mg - 13 P - 1683 Zn - 1823


Harley Davidson Syn 3 20w-50

Si - 5 Na - 0 Mo - 1 Bo - 271 Ca - 1342 Mg - 740 P - 997 Zn - 1068


Mobil 1 MX4T 10w-40

Si - 2 Na - 6 Mo - 91 Bo - 248 Ca - 2483 Mg - 12 P - 1663 Zn - 1802


Look at the differences between the HD and V-Twin oils. The V-Twin has a lot more anti-wear components than the HD oil. Everything else pretty much equals out, though HD uses more Magnesium to make up for less Calcium as acid neutralizers. Looks like the V-Twin is the superior oil based on the additive package.

Now compare the V-Twin to the new Mobil 15w-50 car oil. Once again the V-Twin has more anti-wear additives. But the car oil has more acid neutralizers, indicating it could probably go longer between changes.

Something unusual showed up in the amounts of Molybdenum. Moly is a friction modifier, and too much of it could cause clutch slippage if used in an HD primary. Strangely, the V-twin shows more of it than the car oil, though it is recommended for primary use. The HD oil has essentially no moly, which goes with their recommendation of using it in the primary. Based on these analyses of the Mobil 1 oils, I would not have a problem using the car oil in my primary.

My conclusions? Mobil 1 V-Twin is the best of these oils. The slightly lower acid neutralizers than the car oil doesn't really matter if you change oil every 3000 miles. The HD oil is inferior in every respect that matters. You're paying the HD premium if you use it.

I've been using the Mobil 1 15w-50 "red cap" car oil for over 60k miles in my Evo Softail. I chose a synthetic oil for its ability to withstand the extremely high temperatures in Texas. The Mobil 1 car oil more than meets the requirements of an air-cooled HD engine, and is 1/2 to 2/3 the cost of the motorcycle oils. I'll switch to the new Mobil 1 15w-50 car oil for my engine, and will also use it in my primary. I'll continue to use a synthetic gear oil, 75w-90, either Castrol or Mobil 1, in my transmission.