Originally Posted By: triodes
The new Indian Motorcycles are specified to take a semi-synthetic oil meeting API-SM and ILSAC GF-4 standards. 20/40 weight.
To me, these are car oil specs.
Can someone enlighten me here on what this is about or throw some light on the situation?
I took a look at both Victory/Indian websites and they all appear to have a wet clutch design. It's interesting that they recommend the use of an oil that meets API-SM and ILSAC GF-4 rated oil (which indeed are PCMO specs). Regardless, I checked further into their 20W40 and found they state it's formulated without the use of friction modifiers and also prevents clutch slippage.
My best guess as to why they want you to use the 20W40 and those specs is possibly two fold. For one, they are one of the only suppliers of 20W40 that you can get (Yamalube 20W40 is strictly for outboard motors, 20W50 is now recommended for the big twins), this way they'd be nearly guaranteeing you're using their approved/designed oil (nothing wrong with that since they state it's specifically formulated for the Victory/Indian line). Besides it being a unique viscosity, perhaps they decided to go with the 20W40 over the 20W50 because it could be formulated with less VII's thus decreasing the probability of shear, but none the less as Robster showed in his 4500 mile UOA it sheared down to a 30 grade (which seems like a rather low viscosity for a big displacement air cooled twin).
After reviewing his UOA (which is technically Victory 20W40, but I think we can safely assume it will be virtually identical for the Indians), I noticed the Zinc/Phosphorus levels seemed more in line with the SM specs calling for between 0.06-0.08 PPM (even though they technically don't have to meet that requirement because their viscosity is not between the 0W20-10W30 oils) instead of JASO MA specs of 0.08-0.12 PPM, but technically since we don't have a Virgin analysis we can't be absolutely sure of the initial levels. I further noticed its higher content of Magnesium (810) and when compared to virgin analysis of Mobil Delvac 15W40 from PQI America the additive pack is relatively similar (except for higher Calcium/Zinc content, and Moly levels in the Delvac).
The last thing I can think of is that perhaps they don't want their "American" brands to be associated with a Japanese JASO MA spec, but I could very well be wrong on that. None the less, since they call for a 20W40 I think you'd be safe using their brand of oil, and could safely run a 15W40 HDEO like Clevy and be safe, along with any JASO MA 20W50 for higher temperature protection. If under warranty though, I'd definitely stick with their line for the duration of your warranty.