What oil viscosity to use?
Thread Starter
Senior Member
SuperSport
Joined: Jul 2008
Posts: 987
From: San Diego, CA
What oil viscosity to use?
I've seen plenty of threads about what oil brand, but viscosity is never mentioned.
Maybe that means it's a dumb question?
I put 20w50 in on the last oil change. Should I be running 10w40 instead? I'm in a mild climate, ride it often, and care more about wear protection than squeezing a tiny bit more horsepower out of it.
Maybe that means it's a dumb question?
I put 20w50 in on the last oil change. Should I be running 10w40 instead? I'm in a mild climate, ride it often, and care more about wear protection than squeezing a tiny bit more horsepower out of it.
Rooster Wolf
Back Marker
Joined: Apr 2008
Posts: 103
From: Knightdale, NC
Have to admit, I've wondered the same thing. Why is it that it's typically 20w-50 for the twins, and 10w-40 for the I4 engines? There are some brands, such as Amsoil, that market 20w-50 for V-twin engines. Since you run only 2 cylinders, do you "need" a different weight oil? Honda recommends 10w-40 for our Hawks, I used 20w-50 last oil change because I was given a particular brand to try.
Senior Member
Superstock
Joined: Mar 2007
Posts: 268
From: San Diego
Ooh, an oil thread. This might get out of hand.
Annyway, IMO 20w50 is fine. 5w40 is the lowest I'd go (Rotella).
Don't get anything 30w. Too thin.
As far as wear protection goes, you need an oil that won't shear over time. Rotella is good at this, both the conventional and synthetic. Prices for the blue jug synthetic just went up to $20/4qts of this stuff, just enough for the hawk. Conventional is $10 IIRC.
I'm switching over to the red cap Mobil 1 15w-50 for the next change. I've heard good things about this stuff, gonna try it out. Since the oil change intervals are rather short on a bike, I would run either a Purolator standard/pureone or a Walmart Supertech. They are very good for the price, featuring a silicone anti-drainback valve and other features that won't be matched for the price .
depending on my mood (and wallet), rotella 15w-40, synthetic rotella 5w-40 or mobil1 15w-50 will be cycled through the engine. San Diego has optimal weather conditions so either one is fine.
Annyway, IMO 20w50 is fine. 5w40 is the lowest I'd go (Rotella).
Don't get anything 30w. Too thin.
As far as wear protection goes, you need an oil that won't shear over time. Rotella is good at this, both the conventional and synthetic. Prices for the blue jug synthetic just went up to $20/4qts of this stuff, just enough for the hawk. Conventional is $10 IIRC.
I'm switching over to the red cap Mobil 1 15w-50 for the next change. I've heard good things about this stuff, gonna try it out. Since the oil change intervals are rather short on a bike, I would run either a Purolator standard/pureone or a Walmart Supertech. They are very good for the price, featuring a silicone anti-drainback valve and other features that won't be matched for the price .
depending on my mood (and wallet), rotella 15w-40, synthetic rotella 5w-40 or mobil1 15w-50 will be cycled through the engine. San Diego has optimal weather conditions so either one is fine.
Last edited by Anto; Sep 23, 2008 at 05:41 PM.
I was running Rottela when my CCT failed, yea! combined threads!
Thread Starter
Senior Member
SuperSport
Joined: Jul 2008
Posts: 987
From: San Diego, CA
I think the "V-twin" oil you see is intended for air-cooled motors. It's thicker simply because the oil runs hotter (and probably also because harleys leak more.)
It's really a misnomer to call it v-twin oil. I can't see a bit of difference between the water-cooled V-twin and inline motors as far as oil goes, except maybe that the inlines spin up higher.
It's really a misnomer to call it v-twin oil. I can't see a bit of difference between the water-cooled V-twin and inline motors as far as oil goes, except maybe that the inlines spin up higher.
Senior Member
MotoGP
Joined: Aug 2007
Posts: 2,547
From: Way Out West
Senior Member
MotoGP
Joined: May 2008
Posts: 3,452
From: San Clemente, CA
20W50 is a little heavy for Central California Coast. Go with 10W40 as Honda recommends. 
Wait, you're in SD, not SLO. But the answer is the same.
Wait, you're in SD, not SLO. But the answer is the same.
Last edited by VTRsurfer; Sep 23, 2008 at 08:39 PM. Reason: add to post
Ejection Seat Fixer
Squid
Joined: Jun 2008
Posts: 82
From: PA
I am thinking 15W45 splits the question just fine 
I would just follow what the manuals say and they recommend 10w40.... and I would go with that unless we're talking 90-100 degree plus days , lots of stop and go traffic driving, then i might consider 20w50....
20w50 , according to the maunal is good to use from 30deg F and higher temps, where as 10w40 is (supposedly) good from 10 deg F and higher temps
So really, unless its going to get below 30 deg F, you'd still be safe with 20w50...
I would just follow what the manuals say and they recommend 10w40.... and I would go with that unless we're talking 90-100 degree plus days , lots of stop and go traffic driving, then i might consider 20w50....
20w50 , according to the maunal is good to use from 30deg F and higher temps, where as 10w40 is (supposedly) good from 10 deg F and higher temps
So really, unless its going to get below 30 deg F, you'd still be safe with 20w50...
Crash
Superstock
Joined: Jan 2008
Posts: 309
From: nashville
u r an idiot for using car oil! motorcycle oil has additional additives not found in car oil, and you can buy honda GN4 10-40 for 4.25$ a court, if thats 2 expensive you need to get a job, i work at one of largest dealerships in US and work on motorcycles on the side, it dont have to be honda oil, any motorcycle oil will work and if its cold where u live use low weight, if really hot u can use heavyier weight dont listen to Ratty sorry
Junior Member
Squid
Joined: Sep 2008
Posts: 18
Hell I ain't advising anyone what to do, do as you like, I run car oil, have done for MANY years without ANY issues. If anyone does decide to try it though make sure you use stuff WITHOUT friction inhibitors (some car oils have them bike oils don't) otherwise your wet-clutch will slip like a bastard.
I didn't just wake up one day and start shoving car oil in my bike, I spoke in great length to two guys who work in the oil industry on this very subject I was supprised to find out exactly the 'difference' really is.
But like I say, I ain't advising anyone to do anything. We're all capable of making our own decisions, do your own research and make your own choices.
Senior Member
Superstock
Superstock
Joined: Apr 2007
Posts: 321
Sport Rider magazine did a through, multi segment article that compared a ton of different oils, both Auto and MC and found that while some of the moto oils had pretty different additive packages, the stuff that really counted was the quality and heat resistance of the base ingredients. Mobil 1 was among the highest ranked. Good Auto oil is fine. Motorcycle engines on the street are far less stressed then an auto engine (power to weight) with the real difference being that the transmission and engine are shared in an MC.
RUNLEVELZERO #99
SuperBike
Joined: Jan 2007
Posts: 2,218
From: Skokie
I normally run M1 15w-50 but for this month (cold to date) and mothballing, I'm running Rotella-T syn 5w-50 now $22/gallon at WallyWorld! Any good multi-w syn even down to 5 weight is good but with M1 now over $6.30/qt watch for it on sale. Pep Boys has sales for $30 for 5 qts + a filter which you can use in your cage (or upgrade if the rebate allows to a Purolator PL14612). The PL1612 has better media, bf valve & capacity than OE but requires minor chin fairing trim. The WallyWorld (WalMart) SuperTech ST7317 (less than $3!) and Purolator Pure One PL14610 are 3.25" long; too long unless you really hack your chin fairing.
see http://www.peterverdonedesigns.com/motoroil.htm
and http://motorcycleinfo.calsci.com/Consumables.html
see http://www.peterverdonedesigns.com/motoroil.htm
and http://motorcycleinfo.calsci.com/Consumables.html
Senior Member
MotoGP
Joined: Aug 2007
Posts: 2,547
From: Way Out West
I normally run M1 15w-50 but for this month (cold to date) and mothballing, I'm running Rotella-T syn 5w-50 now $22/gallon at WallyWorld! Any good multi-w syn even down to 5 weight is good but with M1 now over $6.30/qt watch for it on sale. Pep Boys has sales for $30 for 5 qts + a filter which you can use in your cage (or upgrade if the rebate allows to a Purolator PL14612). The PL1612 has better media, bf valve & capacity than OE but requires minor chin fairing trim. The WallyWorld (WalMart) SuperTech ST7317 (less than $3!) and Purolator Pure One PL14610 are 3.25" long; too long unless you really hack your chin fairing.
see http://www.peterverdonedesigns.com/motoroil.htm
and http://motorcycleinfo.calsci.com/Consumables.html
see http://www.peterverdonedesigns.com/motoroil.htm
and http://motorcycleinfo.calsci.com/Consumables.html
Also, there is another way to use that Pure One, or any other 3.25" filter.
Simply remove the chin fairing and run without it. That's what I do.
Senior Member
SuperSport
Joined: Aug 2007
Posts: 714
From: Fredericksburg, VA
Molybdenum is the friction inhibitor in most car oils.
Seeing the "twins" oils always throws me off too, but then I remember that I ride a rare breed of twin, one that is tuned for high performance and high rpms. I guess they label it like that to make the cruiser riders and Hardley riders feel special causing them to pay extra for cheaper oil.
I do have some Screamin Eagle Synthetic 20w-50 I need to use. I wonder if that would be ok?
Seeing the "twins" oils always throws me off too, but then I remember that I ride a rare breed of twin, one that is tuned for high performance and high rpms. I guess they label it like that to make the cruiser riders and Hardley riders feel special causing them to pay extra for cheaper oil.
I do have some Screamin Eagle Synthetic 20w-50 I need to use. I wonder if that would be ok?
RUNLEVELZERO #99
SuperBike
Joined: Jan 2007
Posts: 2,218
From: Skokie
I'm guessing you know (and simply mis-typed) that the Rotella Syn is actually 5w40. Yep, typo
Also, there is another way to use that Pure One, or any other 3.25" filter.
Simply remove the chin fairing and run without it. That's what I do. Sacrilege but trimming is possible and I run heat wrap and a custom shield to minimize the hdr heat transfer and the chin frg hides it
Also, there is another way to use that Pure One, or any other 3.25" filter.
Simply remove the chin fairing and run without it. That's what I do. Sacrilege but trimming is possible and I run heat wrap and a custom shield to minimize the hdr heat transfer and the chin frg hides it
Molybdenum is the friction inhibitor in most car oils.
Seeing the "twins" oils always throws me off too, but then I remember that I ride a rare breed of twin, one that is tuned for high performance and high rpms. I guess they label it like that to make the cruiser riders and Hardley riders feel special causing them to pay extra for cheaper oil.
I do have some Screamin Eagle Synthetic 20w-50 I need to use. I wonder if that would be ok? ok but otherwise inferior
Seeing the "twins" oils always throws me off too, but then I remember that I ride a rare breed of twin, one that is tuned for high performance and high rpms. I guess they label it like that to make the cruiser riders and Hardley riders feel special causing them to pay extra for cheaper oil.
I do have some Screamin Eagle Synthetic 20w-50 I need to use. I wonder if that would be ok? ok but otherwise inferior
Gas tank OS plus XXrange tank
Senior Member
MotoGP
Joined: Aug 2007
Posts: 2,547
From: Way Out West
At least the Pure One filter comes close to matching the color of my '03, something Honda didn't bother doing when they stuck that little plastic afterthought on the bottom of the bike!
To each his own. I like the look of the bike without it. Being able to use the longer filter is a bonus.
To each his own. I like the look of the bike without it. Being able to use the longer filter is a bonus.
Junior Member
Squid
Joined: May 2020
Posts: 2
Have to admit, I've wondered the same thing. Why is it that it's typically 20w-50 for the twins, and 10w-40 for the I4 engines? There are some brands, such as Amsoil, that market 20w-50 for V-twin engines. Since you run only 2 cylinders, do you "need" a different weight oil? Honda recommends 10w-40 for our Hawks, I used 20w-50 last oil change because I was given a particular brand to try.
Senior Member
SuperSport
Joined: Jul 2018
Posts: 565
There is a chart that specifies which viscosity to use and it is based on bearing clearance and operating temperature. Those are the two primary factors. After that it comes down to application, i.e. motorcycle, car etc. After that wet clutch vs dry clutch after that combined or detached transmission. The chart is published by Driven racing oils and I know them to be very knowledgable and reputable.
https://www.drivenracingoil.com/
AV
PS, I also run "diesel" oil from time to time. No issues "shear" be damned.
PSS, Until a commentator has sent a sample to a lab such as Blackstone, they have no legs to stand on regarding oil and they are not entitled to an opinion.
https://www.drivenracingoil.com/
AV
PS, I also run "diesel" oil from time to time. No issues "shear" be damned.
PSS, Until a commentator has sent a sample to a lab such as Blackstone, they have no legs to stand on regarding oil and they are not entitled to an opinion.
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