Because 100% synthetic oil is just better oil. If somebody can find a documented test too prove otherwise I'll believe it, but I havent seen one and dont think any exist since Ive done many of the tests myself and seen first hand the differences and the truth. There are better synthetic oils though, in both cost and quality, and at $12 a quart that oil should have some gold in it cause I pay $26.05 a gallon, thats $6.52 a quart, for the best motorcycle oil on the market, Amsoil MCV 20/50, and it is test proven.
I do pay $10 to get dealer prices from Amsoil, but I also buy oil in bulk for 6 different Trucks and 4 other motorcycles for the year all at once. The ten bucks plus the shipping charges for the 18-20 gallons of oil I buy a year dont add much to the per quart price of my cycle oil, maybe 50 cents.
Clean and fresh is good for all engines no matter what oil you are using, and you can never go wrong by changing it more often, but obsessively changing your oil isnt enviromentaly friendly or cheap. I like too change my oil more often than I have too in a scooter with a wet cluth because I like them to last a long time with few engine problems, about every 3000-5000 miles depending on how it smells and tastes, even though I could go 2 or 3X that regular change interval according too UOA of other KLRs using Amsoil MCV full synthetic 20/50 It is still shear stable. in grade, and the TBN is still good around that mileage. Regular old dino/mineral oil shears down about half its viscosity every 1000 miles in a KLR. That means if you are using a premium dino 10/40 oil it has the film strength of WD-40 after 1500-2000 miles. That includes Rotella, Delo, Castrol, and any other Hydrocracked oil that is being marketed as synthetic. I do change my filter more often though, 2 or 3 times before changing the oil.
Hey Joe, we use that ISO SYN Delo in our trucks as well. Its decent oil specially when your truck holds gallons of it in the sump, but its not synthetic, and it may contain alot of MDS from what Ive read, which is one reason it is good in the trucks, ya might wanna check that out, change it often, and if your clutch starts slippin flush the engine and change the oil.
Real synthetics are PAO, Esters, and polyesters, and/or blends of those "synthetic" oils. Dino blended oil is a scam, dont waste your money. Mobil 1 is good stuff and costs about $6 a quart here at Wally World for their V-Twin super syn. You cant go wrong with it. Their auto line of oils should not be used in the KLR.
Unless you live where it is below the freezing point of water during your riding season there is no reason to use a lighter oil in the KLR than 20/50 synthetic, it flows fasterand pumps easier at -10C than a dino/mineral 10/30. Got a deep freeze? See for yourself.
Thats my take, experience, and info on oil. If you wanna use the best, its easy to get. If you wanna use something else thats fine too, just dont say its the best without documented proof.
Daniel