Fuel Mixture

[lefty]

Craftsman P2 Trimmer

Model 316.79190
S/N: 1E128DB0924

This machine came in from my brother and it says 40:1 for fuel. I've been reading some stuff online saying that with the newer oils should be run at 50:1. Should I run this according to the specs on the machine or should I be going 50:1 with modern oil?

[Arkie]

IMHO:

I would mix it 40:1 and if it slings a rod you done your part on the mix. (not that you are saving much by 40:1 vs 50:1)

I've got some old chainsaws that owners manuals recommend 30W not detergent motor oil and mix of 24:1, some at 32:1 and this mix will smoke out the mosquitos, I mix these old model saws at 40:1 with the late model 2 cycle oil mix unless mosquitos are going to be a problem and never had any issues with my engines.

If anyone ask me how they should mix for anything I tell them to read the owners manual and manu recommendations.

In oz mix terms for example of gasoline or oil:

1 gallon of gas =128 oz divided by 40=3.2 oz oil for 40:1 mix

1 gallon gas =128oz divided by 50= 2.56oz oil for 50:1 mix

or 102 oz of gasoline with 2.56 oz oil = 40:1 mix

[KE4AVB]

Personally I use and sell a Pro Mix that is a multi-mix oil. I use it the the old Homelites that are 16:1 all the way up the newer equipment like my Husqvarna 450 that uses 50:1. It is a semi-synthetic oil with stabilizers. It is one bottle/package per gallon of fuel. I got tire of having multiple cans of fuel mixes going bad and I don't worry equipment specific mixes.

And Sunbelt just upgrade my stock to an Ultra Pro Mix which is a 100% synthetic blend.

[lefty]

Thanks guys. I was not aware that there was a universal mix. I will definitely pick some up. 99% of the fuel I mix in my little 1-gallon can is for 50:1. Doesn't make sense to keep a 2nd or 3rd can lying around just going bad.

[creia]

A few years ago my son restored a 1979 Yamaha YZ80 Motocross bike (very fast little bike!) . The original owner's manual called out for a 16:1 mix. I posed this same question on a vintage MX bike forum and the concensus was that with the newer better "modern" oils a mix of 32:1 was correct which we did w/o any problems.
Michael

[lefty]

Interesting. Does anyone have any thoughts regarding running 50:1 for a short duration? Just to get the machine running? Then the owner can run 40:1 if they choose.