My Klutz Moment - 75:1 Mix For Husqvarna 550XP

[bigcitymike]

Manual says 50:1, and my bonehead reading of the scale on the side of the VP full synthetic 2-stroke oil led me to mix a ratio of about 75:1 in my brand new Husqvarna 550XP. I ran a gallon at that mix rate, before realizing my error when mixing a new batch. So I guess it's really broke-in now, just wonder how bad I prematurely added wear to it. After mixing the appropriate amount (50:1), I've run about a tank of that through. Honestly can't say the saw runs any different (not that I expected it to).

Without scoping the bore, no way to really tell what damage was done. Anyone ever run the VP full synthetic 2-stroke oil that thin (75:1)?

 

[Brian123]

You should be fine, it's not like you were running the saw at full throttle the whole time. 75 to 1 is not that thin, 100 to 1 is a different story.

 

[dlundblad]

I’m sure you’re fine. Amsoil Saber can supposedly be ran at 100:1. I am not that brave and mix it at 50:1 still.

 

[tnt_motorsports]

FWIW, oil mixture is only 1 piece of the saw break-in. Warming it up and no extended full throttle runs are probably just as big a factor. If it's still running I'd say you are fine. As a side note I run my 2 stroke stuff at 40:1. It's just a little added protection because IMO, most 2 stroke stuff doesn't need a throttle trigger, it just needs a switch, on & off!

Just my $0.02

 

[bchannell]

Well, don't feel bad. I was at a flea market years ago and bought some Amsoil 100:1. Went home and mixed it up for my Lawnboy. Started mowing and after about 15-20 minutes it locked up. I let it cool and it did the same thing again, duh! I had mixed it 200:1. Amazingly the Lawnboy survived, and with proper mix, ran fine. It happens.

 

[Cujet]

The VP oil is diluted to pour and mix easily, so your 75 to 1 mix was not really an ideal situation. From an engine life and protection point of view, use 4 ounces of oil per gallon, as 32 to 1 was in our testing, about the best overall choice.

The good news is that these engines are very well made, and a new engine has plenty of cylinder bore oil retention. It is unlikely you hurt the crankshaft, as oil migration through these engines is RPM dependent and chain saws do spend time at idle where oil is retained well.

 

[ripcord]

An easy way to mix oil is just remember that

• 3 ounces per gallon for 50:1 (43:1 actual)
• 4 ounces per gallon for 32:1
• 8 ounces gives 16:1 for antique stuff without roller bearings

The actual formula is:

1 / N X 128 = ounces of oil per gallon

Where N is the mix ratio desired

So 1 / 50 X 128 = 2.6. Rounding up to 3 ounces works out like 1 / 43 x 128 = 2.97 which is going to be close enough for all practical purposes.

 

[Fordiesel69]

Back from your high school days, 1/n x 128 = Where N is the diethical evolute of retro grade temperature phase disposition.

Especially landscapers brag about using Amsoil Saber at 100:1 thinking it makes them some record holder. Seems their equipment runs, albeit not lasting as long.

These 550XPs will most likely pop a crank seal / bearing before the cylinder wears out. These are really awsome saws, and the 545, 550XP, 555, 562XP, 565, and 572XP are really powerful for their weight / size.

I get concerned once strato saws start to accumulate hundreds of runs hours, the ports and piston skit can start to shine up (loose oil retention grooves) near the strato ports. This will increase wear even further. Rich oil mixtures 32:1 / 40:1 will slow this down a bit. My 555 seems to feel the same to me running it at 40:1 vs 50:1.