Viscocity Change / MC Specific oil vs. Non in Dry Clutch Engine? - - The Ultimate Ducati Forum
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post #1 of 2 (permalink) Old Apr 22nd, 2018, 5:05 pm Thread Starter
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Location: St. Albans, Vermont, USA
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Viscocity Change / MC Specific oil vs. Non in Dry Clutch Engine?

So, my "Local" dealer uses mostly 15w-50 for oil. My owners manual says 20w50, LT Snyder's book says 10w50 and my Haynes manual says 10w40.

Okay, there's the baseline to my question.

I was once told, at an early age to be wrenching on vehicles, that switching brands usually isn't a problem, but you want to stick with the same viscosity unless you want to start burning oil. Not sure how true that is, but I've always tried to keep it in mind and have usually been just fine following that mantra. As I face an overdue oil change on my ST2, finding 15w50, which the bike currently has in it, is turning out to be a bit of a nightmare. I have some Spectro Golden 10w40 already in my garage that I could use, but I don't think that bike has ever had that in it. SO, should I continue searching for 15w50, follow LT's suggestion and go 10w50, or go with what I have? (Or follow OEM and do 20w50?) And if I DO switch viscosities, am I asking for trouble as per the old wisdom I was raised with?

Then that leads to my next question. I was also once told that the main difference between Motorcycle specific oil and regular automotive oil was that bike oil was designed not to effect clutch operation as many auto oils have extra additives that cling and coat and can cause an oil bath clutch to slip. As I have a dry clutch bike, would I be okay and grabbing oil at the local AutoZone (if they have the viscosity I want), or is there some other reason to avoid car oil and stick with MC specific oil?

My biggest issue is that finding an open bike shop around my area is nearly impossible with my work schedule. My "Local" duc dealer is an hour and half away, overpriced, pretentious, and I have had problems with them before (why drive three hours for oil?). I actually had to get an oil filter at the local Harley Davidson Dealer (That was actually a really fun conversation! ), and was only able to do that because they are open on Sundays. Really trying to avoid mail order.

Okay. I think I've laid down enough fuel. Time for someone to throw in a match so we can watch this thing burn up. Thanks, all!

2000 Ducati ST2 Blue (The Rare Blue Duc), Join the AMA today!!
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post #2 of 2 (permalink) Old Apr 22nd, 2018, 6:32 pm
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Location: Proctor, VT, USA
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Read your Owners Manual. If your local average temperature in Vermont is anywhere between below freezing 14F and 100F then you should use a 40 weight or 50 weight oil. Because Ducati uses the same oil to lubricate the transmission, the higher viscosity if preferable since over time the transmission gears cause the viscosity to decrease.

The 10W, 15W or 20W part of the rating simply indicates what the viscosity will be at low temperatures to aid in reducing drag during the initial start.

You should change to a lower viscosity if you plan to ride mostly when the average temperatures are low.

Since the dry clutch doesn't run in an oil bath it makes no difference what viscosity is used. Higher viscosities simply assure adequate oil pressure at higher operating temperatures but if you're not going to experience these temperatures, running a higher viscosity oil just gives you higher pumping losses. Hence the recommended oil viscosity chart in your Owners Manual.

Engine oils contain additives called friction modifiers (usually molybdenum-based) that can lead to clutch slippage in wet clutch motorcycles. This is a compelling reason to avoid some oil formulations that contain added amounts of friction modifiers to meet USEPA fuel economy mandates. Consequently, wet-clutch slippage can be a problem when you use lower viscosity oils that are designated "Energy-Conserving" on the bottle. In other words, you're less likely to experience wet clutch slippage with the higher viscosity 15W-50 grade oils that are not able to be designated energy conserving and therefore have not been mandated to contain additional amounts of molybdenum.

I recommend and use Mobil 1 15W-50 full synthetic automobile oil in a dry clutch Ducati and change it at 3,000 mile intervals. Available everywhere.
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