Transmission oil mistake...

[Captned]

Hello all,

I just changed oil and oil filters for the mains and the transmissions.(Allisons) When I was refilling the starboard tranny, I accidently put in 5 quarts of 30 wt. Didn't look closely at the bottles when I bought them. I had two quarts of 40 wt in the tranny already and 1 1/2 quarts of 40 wt. in the screw on filter. So I got a mix of 5 qt. 30 and 3 1/2 quarts of 40 wt.

So I'm running on 34 wt.????

Should I pump it out and start again or should I leave it in?

I use the boat about 120 hrs a year.

Thanks in advance,

Capt. Ned "too dumb to look at the friking bottle before I put it" Hickel
Miami Beach

 

[Boatsb]

I would use all 40 in my twin discs and if the allisons use the same its worth changing it out as the lower viscosity would be the issue. If they are OK with 30 than its probably ok as long as the oils are all of the right type. If it were me I would just warm them up, Pump it out and put in fresh 40wt.

Just so you feel a bit better I have done this more than once in my years maintaing boats. I even put trans fluid in the engine once before ( 1/2 qt before I discoverd my mistake)

 

[MikeP]

Put some 50 in there if you can get it. Viscosity is pretty simple - if you put in equal 30 and 50, you have 40 (as long as it's the same brand/type of oil). If you can find 50 (I admit I never tried) I'd add that proportionally and not even worry further about it.

 

[Nonchalant1]

FYI = The DD=Allison manual says to pump out the old oil, then fill with 10 wt. and run until warm, pump that out and refil with straight 40 wt. Allisons werre designed to be pumped out by a hose over the dipstick tube which will never fully empty it, so Allison has us running a little 10 wt. with a lot of 40 wt. all the time.

I disagree that if you mix 30 wt and 50 wt you get 40 wt. I think you get 40W-50 oil, which is different. If it were me, I'd suck out as much as possible, without changing the filter or 3 bolt flange, and refill with straight 40 wt.

Doug Shuman

 

[SKYCHENEY]

I think MikeP is right. Straight weight oils are a different animal than mulit-visocity. Allison recommends either 40wt or 30wt. I don't believe that a mix of the 2 would be a problem. Like you said, 34wt. As long as they are the same oil brand and type, the weights can most likely be mixed, especially in a transmission.

 

[yachtsmanbill]

Doesnt DD recommend 30W below like 50F or there abouts? ws

 

[SKYCHENEY]

I think that is right, but many people use 30wt in all weather because it stops the slow shaft turn in neutral that Allisons are know for when they are cold.

 

[Boss Lady]

Viscosity and sheer strength are the two critical factors. SAE 30 or SAE 40 are measured at temperature. If the manufacturer specifies SAE 40 then you should use SAE 40 only. Now in reality, if you have a mix of 30 and 40 will it cause a problem? If you are operating moderately, in my opinion you will probably be just fine. There is a difference between SAE grades and the "W: grades (10W40). SAE is all oil and is the best. The W grades are a base oil with polymer additives. The oil is a 10 weight viscosity oil with polymer extenders that make it behave like a SAE 40 weight oil. The 10w40 flows like a 10 weight at zero degrees temperatue, but behaves like a 40 weight at 100 degrees C. Nice trick for a multi-season oil. But the reality is that a natural oil is still the best. This is why DD specifies SAE 40.

 

[Genesis]

30wt is fine in Allisons if they're not too highly strung; Allison SAYS either is acceptable.

Personally, I always ran the 40. I like the higher shear strength......

No multi-grade oils in Allisons! (None in DD 2 strokes either)