Takeuchi spec VG 32 -4F to 86F , VG 46 15F to 104F, VG68 40F to 150F.
I can email the chart in the operation manual .No where does it say any about 10w30 motor used.
Yes Ok, and 46-68 are ~20w equivalents. Not 10W. I'm not going to argue that some guys get 10k hours on a machine, but those who do that are WAY MORE service type "nerds" than the average joe and actually DO the servicing like with filters n such at proper intervals which is going to make there machines last a a lot longer. My point it, the Manufactures make there recommendation from experience w THEIR machines. Something COULD be better, but in most cases they make a good choice.
I know of 3 Type of machine "users".
There are the BOB's: They use them and abuse them and unless some light comes on telling them something it wrong they just keep going.
There are the CLIFF: They WANT to service there stuff as per the manual, but just dont find the time to do it. They do eventually get to it but it could be way after it was required.
Then there are the CLARKS: I'll make this simple, you can eat off there garage floor...no need to say how well they care for their machines.
Clarks machines can make it to 10k.....most Bob and Cliff machines don't ever seem to get there. I think it is wise to CONTACT the manufacturer then "just take some dealers word" on what to use, like ToolKing's point is made.