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Discussion Starter #1
Came across this question and answer which seems to make a lot of sense to me.

Is it okay if I use engine oil rated 20W50 instead of the 10W40 oil stated in the vehicle manual since I live in a tropical location?
No, your engine is designed to pump the oil recommended at full working temperature which is around 100 deg C. The fact that your air temperature is around perhaps 30 deg C is irrelevent.
Any 50w oil, whether 5w-50, 10w-50 or 20w-50 will be too thick at 100 deg C and will fail to flow as fast as the engine maker intends so will not carry heat away as well as the intended 40w.
Furthermore, at start-up, the 20w-50 will be lots thicker than the 10W40 and will pump so slowly you’ll get a high rate of engine wear even before the oil gets to temp.
There’s a reason engines only lasted for at best 100,000 miles in the ‘70’s and it was because they used 20w-50, the 20w part causing extremely high wear before the oil was hot.
A lot of 10W40’s are fully synthetic which can handle much higher temps than any mineral oil so high ambient air temps are simply not an issue. The 15 degree difference between the 15 deg C on a cold day in the UK, and the 30 deg C you might enjoy is literally irrelevant compared to the 300+ deg C the oil is good to.
 

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Yamaha factory changed the original 20-40 oil spec for the Warrior and the other Star big cube motors. Your Yamaha dealer can confirm. The manuals were all dated prior.

Now its 20-50 summer 10-40 winter. But it turns out 20-50 all year is good. Even on Mt Hood Oregon and the high Sierra mountains and the hot dry deserts. In the USA anyway. I run 20-50 full synth all year, and have for years now.

Separate, I think in 1960~1970's we used non-detergent 30 weight oil in metric bikes and the harleys were mostly 50 weight. Could be remembering it wrong, maybe 60 weight. Motors back then didn't get to 100k because manyfacturing tolerances were what they were. Thousands of inventions and discoveries later, motors last longer.
 

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Discussion Starter #4
Yamaha factory changed the original 20-40 oil spec for the Warrior and the other Star big cube motors. Your Yamaha dealer can confirm. The manuals were all dated prior.

Now its 20-50 summer 10-40 winter. But it turns out 20-50 all year is good. Even on Mt Hood Oregon and the high Sierra mountains and the hot dry deserts. In the USA anyway. I run 20-50 full synth all year, and have for years now.

Separate, I think in 1960~1970's we used non-detergent 30 weight oil in metric bikes and the harleys were mostly 50 weight. Could be remembering it wrong, maybe 60 weight. Motors back then didn't get to 100k because manyfacturing tolerances were what they were. Thousands of inventions and discoveries later, motors last longer.
And which particular 20w50 do you use? What's the mileage on your ride? You still running the original Valve Lifters or did you have them replaced? If so at what mileage and was it because they were worn or noisy?
 

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I ran Mobile 1 20/50 yr round n Bosch filter
Warrior had 115k miles when I totaled it
All original engine n components

Second warrior bought with 11k miles
Mobile 1 20/50 n Bosch filter since first oil change
Now almost 50k miles all original engine components....

Bro dont over think it..


Sent from my SM-A102U1 using Tapatalk
 

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From my posted data sheet:

Wet-Clutch Motor Oil:
1. Amsoil 20W50 MCV Full Synthetic [favorite]
2. Mobil 1 20W50 V-Twin Full Synthetic
3. Yamalube4 10W40 or 20W50

Bike performs aggressively on all road types and elevations, partly thanks imo to Avon Storms. Motor internals are all original 102ci although I have certain spares for the day. Fact is, with the factory nikasil lining and semi-dry-sump, this beast is tolerant. I run 5k~7k miles between oil changes with Bosch and Amsoil, no lifter noise beyond normal. Drained oil most often has some life left (no unusual grit content or metals).

Yamaha built a heck of a motor and an astounding machine. I push triples when can, like many others here. I do adequate maintenance and the bike is still a grin-factory after ~17 years. Never had a bike this long 🙂
 

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Discussion Starter #7
From my posted data sheet:

Wet-Clutch Motor Oil:
1. Amsoil 20W50 MCV Full Synthetic [favorite]
2. Mobil 1 20W50 V-Twin Full Synthetic
3. Yamalube4 10W40 or 20W50

Bike performs aggressively on all road types and elevations, partly thanks imo to Avon Storms. Motor internals are all original 102ci although I have certain spares for the day. Fact is, with the factory nikasil lining and semi-dry-sump, this beast is tolerant. I run 5k~7k miles between oil changes with Bosch and Amsoil, no lifter noise beyond normal. Drained oil most often has some life left (no unusual grit content or metals).

Yamaha built a heck of a motor and an astounding machine. I push triples when can, like many others here. I do adequate maintenance and the bike is still a grin-factory after ~17 years. Never had a bike this long 🙂
From my posted data sheet:

Wet-Clutch Motor Oil:
1. Amsoil 20W50 MCV Full Synthetic [favorite]
2. Mobil 1 20W50 V-Twin Full Synthetic
3. Yamalube4 10W40 or 20W50

Bike performs aggressively on all road types and elevations, partly thanks imo to Avon Storms. Motor internals are all original 102ci although I have certain spares for the day. Fact is, with the factory nikasil lining and semi-dry-sump, this beast is tolerant. I run 5k~7k miles between oil changes with Bosch and Amsoil, no lifter noise beyond normal. Drained oil most often has some life left (no unusual grit content or metals).

Yamaha built a heck of a motor and an astounding machine. I push triples when can, like many others here. I do adequate maintenance and the bike is still a grin-factory after ~17 years. Never had a bike this long 🙂
Thanks for your answers. I am wondering if I should change to 20w50 full synthetic...I am using Castrol Actevo 10w40 Part synthetic and no problems. Will the 20w50 be better for my Warrior or wont it make much difference to what I am using now? And Desertboy...is a Bosch oil filter better then the High Flo Filtro oil filter I am using?
 

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Discussion Starter #9 (Edited)
Ambient temperatures where you are also tend to be on the warm side, so . . .
It's winter here now so temps during the day are on average between 5 to 18 degrees Celcius. (40 Fahrenheit to 65 Fahrenheit)

Summer averages between 20 to 28degrees Celcius ( 70 Fahrenheit to 82 Fahrenheit)
 

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Discussion Starter #12 (Edited)
What about a 10w50 synthetic? Woud that not be the obvious choice as it gives you the best of both worlds? Perfect for cold and hot weather...why is no-one here using 10w50? All the oil talk is always just between 10w40 vs 20w50. What about 10W50?
 

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What about a 10w50 synthetic? Woud that not be the obvious choice as it gives you the best of both worlds? Perfect for cold and hot weather...why is no-one here using 10w50? All the oil talk is always just between 10w40 vs 20w50. What about 10W50?
Do your research on-line and also shop your area to see if its available, noticing any reduction in technical specs including film thickness at operating temperatures. If its okay with you then there you go!
 

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I also have been using Mobil Syn 20/50 for as long as I can remember and it just loves it. Been stuck in traffic in Daytona where some bikes I rode with had shut off to protect the motor while the Warrior did just fine....no funny noises and kept chugging along.
 

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Discussion Starter #15
Good to know Hefty and thanks Arizaona for the good advice...I will follow up. Hefty what mileage has your Warrior done and are you still running with the original lifters?
 

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My first Warrior had almost 60k and it ran like a top.
Now this Warrior I have had for a few years already and she was a little neglected when received (but at a great price). I knew they were great bikes so I figured I could fix it up. I got her with 20k and now at almost 50k she runs like day one, no weird noises and very crisp/tuned correctly. Both machines were stock internally
 
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