I have 6 quarts of Amsoil 10/40 MC oil left over from my old bike, Now it is time to change over to synthetic on my 06 Road Star, What is the best for the bike 10/40 (the manual calls for 20/40)or 20/50? I getting ready to do 3,500 to 4,000 miles in May over 3 weeks. Do I use the oil I have on hand 10/40 or do I go out and buy some new 20/50 Mobil-1 for V-twins? Thanks for your input.

Pete

Rather than suffer any heartburn, get the Mobil 1 20W-50 V-Twin and go to bed afterwards and get a good nights sleep knowing, you've put in an oil better than the manufacturer suggests. Mobil-1 V-Twin can be purchased @ Walmart and you can get the filter there too. I'm sure others will suggest other synthetics, but for my $$ Mobil-1 is the best. (No, I do NOT work for Mobil).

I smell another OIL DEBATE coming on.....
I personally use Mobil 1 V-Twin 20w50 oil. But I dont think there is anything wrong with AMSOIL 10w40. (My Canadian '05 Roadie manual actually calls for 10w40 cool weather or 20w40 hot weather.)
Are you sure your manual calls for 20w50?
If I were you, I would dump in 4 liters of the 10w40 Amsoil, especially since you already have it onhand. It will work just fine.
If you are riding where the temperatures will be up around 120*F all te time, you might want to go with a 20w50. If you are riding where the temps are not that hot, go with the 10w40 Amsoil you already have on hand. It is still a 40 weight at full engine operating temperatures, just thinner when it's cold on startup in the morning.
Radar is right, Mobil 1 makes a good oil too. Use whichever makes you feel better.
I find that the 20w50 is a bit thick on our 32*f/0*C mornings, and the engine is a little noisy until it gets good oil pressure built up.

I use 20W50, but I am in Florida where the temperature hasn't gone less than 40 at all and hasn't spent much time in the 50's either. This summer it will be 95 on a regular basis.

For the guys that hibernate during the winter and probably won't see 80; the 10W40 will be just fine.

Clifford

You can use your 10w40 amsoil it won't hurt a thing.
That's what I use in my Roadie. Yamaha Quit making the 20w40.
Only put 4qts in with a filter change,not the whole 6

Thanks...........Looks like I'm going down and pick up some Mobil-1 20/50 V twin and filter from Walmart tomorrow and forget about the Amsoil, I'll give it to someone with a Honda........I'm also in Florida.

Thank's for the help.

You'll like the difference..I use Amsoil 20/50. BIG difference from the dino oil.

mongoose84 wrote:
I have 6 quarts of Amsoil 10/40 MC oil left over from my old bike, Now it is time to change over to synthetic on my 06 Road Star, What is the best for the bike 10/40 (the manual calls for 20/40)or 20/50? I getting ready to do 3,500 to 4,000 miles in May over 3 weeks. Do I use the oil I have on hand 10/40 or do I go out and buy some new 20/50 Mobil-1 for V-twins? Thanks for your input.

Pete

Since it's AMSOIL, go with it. It meets the operating temp SAE spec for our Road Star and AMSOIL recommends their 10W-40 over their 20W-50 for the Yamaha. No sense spending more (and more) on oil when what you have will work perfectly fine.

Good luck!

I've heard it said that politics is the ability to compromise...

To that end, I would suggest using the remainder of your Amsoil, then when your weather (temps) improve... add .5 Qts of Lucas Synthetic oil additive... (after draining .5)(The compromise)
You can always got with the Mobile 1 later...

I had Amsoil put in at 5K and it made a world of difference in the engine! I've run 1500 mi. since and I was down about a half... So last weekend, just before a 160 mile run, I topped it of with Lucas and I'm pretty sure I upped my gas milage by nearly 5 MPG!
(Normally I go 140 Miles and take on 3.5 gal... This time I went 168 @ 3.25 gal.)

BTW: I'm running down here in FLA and last weekend was in the upper 80s...

Are you talking about their oil stabilizer? It says it reduces friction. Do you know how? Might be bad for our clutch.