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What happened to 10-40 and 20-50 weight oil

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I'm starting to see that most stores are no longer stocking 10-40 and 20-50 weight oil anymore? I'm seeing at lot of 0-30 and 5-30 weights.

What's going on?

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8 minutes ago, UCLABruins said:

I'm starting to see that most stores are no longer stocking 10-40 and 20-50 weight oil anymore? I'm seeing at lot of 0-30 and 5-30 weights.

What's going on?

What store are you going to?  I haven't noticed that.

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28 minutes ago, UCLABruins said:

Is it okay to use those weights on our bikes?

Use what the mfr. says to use.  They didn't choose an arbitrary weight.  If nothing else a bike store will have the proper oil.

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Rotella is widely available in 15w40.  Works for most applications.  Yamaha recommended 20w40 for my 600, which they don't make anymore, so it gets the 15w40. 

0w20-5w30 are all low viscosity, friction modified energy conserving oils for modern passenger car engines.  Not good at all for high performance motorcycle engines.  Too slippery for wet clutches, too thin for 10000+ RPM.  The catalyst was fuel economy and the engines have been designed to tolerate it. 

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32 minutes ago, turbo dan said:

Rotella is widely available in 15w40.  Works for most applications.  Yamaha recommended 20w40 for my 600, which they don't make anymore, so it gets the 15w40. 

0w20-5w30 are all low viscosity, friction modified energy conserving oils for modern passenger car engines.  Not good at all for high performance motorcycle engines.  Too slippery for wet clutches, too thin for 10000+ RPM.  The catalyst was fuel economy and the engines have been designed to tolerate it. 

Good point on the wet clutch.  It has to be JASO MA for it to work.  The last revision to the standard afaik was like 6 months or so ago.

Edited by cjjeepercreeper
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10W40 has no friction modifiers present but may not be JASO MA certified. It's what I use in a KX250F. No racing. Works fine. 

The popularity of thin oils is to get even 0.1 MPG better on one vehicle which boosts overall MPG for the "fleet" so they can meet Corporate Average Fuel Economy standards that USDOT implements. More info https://www.nhtsa.gov/laws-regulations/corporate-average-fuel-economy

 

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+1 that's because a big part of the recipe for energy conserving oil is low viscosity, after that additive chemistry.  Even some 10w30's can meet jasoMA if they are one the thick end of the 30w range. Honda specs it in a lot of bikes.  In the oil aisle some of the hi milage oils have 10w30 without the starburst.  But ya, 15/40 diesel oil has become the defacto standard for bikers not wanting to spend on bike shop boutique overpriced oils .

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I've noticed this too, that my local parts house no longer stocks 10W-30, 10W-40, or 20W-50.. If you even ask about straight 30 weight they look at you like YOU don't know what you are talking about. They act like straight 30 weight never existed.

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1 hour ago, turbo dan said:

Rotella is widely available in 15w40.  Works for most applications.  Yamaha recommended 20w40 for my 600, which they don't make anymore, so it gets the 15w40. 

0w20-5w30 are all low viscosity, friction modified energy conserving oils for modern passenger car engines.  Not good at all for high performance motorcycle engines.  Too slippery for wet clutches, too thin for 10000+ RPM.  The catalyst was fuel economy and the engines have been designed to tolerate it. 

I like using Rotella T6 which is just a couple more dollars per gallon (at WalMart) than T4. It is synthetic, 5w-40 and JASO MA/MA2 (as is T4) rated. I found the Rotella T4 15w-40 made my clutch feel a bit too "heavy" on cold days.

I'm not sure that the Xw- matters a whole lot for dirt bikes on the engine side - they warm up in what 30 seconds or less... Not really concerned about MPG during warm up...

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I run the 15w40 specifically for the higher base viscosity.  Oils with a higher viscosity index are more likely to shear down significantly when used in a gearbox.  Oils with a higher base viscosity and less spread between them are less likely to shear down over the service interval. 

If I remember correctly Rotella T6 is a group 3 synthetic, which is basically a highly refined petroleum oil.  A group 4 synthetic is a different story.  Being a 5w40 it is a 5w oil that behaves like a 40w at operating temp.  It relies on viscosity index improvers to maintain the high temp viscosity, which is fine in a crankcase, but these molecules tend to chop up going through the gear stack several hundred thousand times.  Before you know it your 5w40 is a 5w15.  A 15w40 will shear down too but is more likely to maintain at least a 30w viscosity towards the end of the service interval.

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A JASO MA certified synthetic in the correct viscosity for your bike is ultimately what you want, if your bike shares the engine and trans/clutch lubricant.  I have found that the synthetics seem to run cooler, best one I've found so far is Lucas.  I was using the Amsoil motorcycle oil for awhile and then figured I'd try the Lucas because it was $2 cheaper at O'Reilly.  Best switch I ever made.  The bike is quieter and runs cooler, I have an oil temp gauge so I know its not my imagination.  20W50 is what I use in summer, 10W40 in late fall, winter and early spring.  BTW, those are the weights the factory recommends. ;)

Edited by cjjeepercreeper

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4 hours ago, UCLABruins said:

I'm starting to see that most stores are no longer stocking 10-40 and 20-50 weight oil anymore? I'm seeing at lot of 0-30 and 5-30 weights.

What's going on?

Ive noticed the same thing in the last few months. It seems it has more to do with shelf space and what sells the most, the 10W40 hasnt been recommended for new cars/trucks for quite awhile.  The trend is now much lighter engine oils.

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4 hours ago, William1 said:

You are oil shopping at the car parts store.

Or Sewing Machine Shop

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