Why 5W30?

[Frank Sorbello]

Was wondering why Power Trac uses 5W30 motor oil in the hydraulics. Why wouldn't you use hydraulic fluid for hydraulic pumps, motors etc... Wouldn't the Robin engine start easier in cold weather with a load using hydraulic fluid vs motor oil.

Thanks
Frank

 

[mikehaugen]

I can't help you much with an explanation but I will say that it is not that uncommon. At work we have industrial hydrualic units and some spec ATF, some sae 30 motor oil, and others spec different grades/viscosities of hydraulic oil. My bunton mower specs 10w40 for the hydraulics. I don't know the reasons, I just do as I'm told. :confused3:

 

[MossRoad]

The hydraulic fluid in my old IH2500b was equivalent to 10. It was not multi-viscosity. It was stuck at 10.

5W30 starts at a 5 and increases to 30 as it heats up. Therefore, 5w30 is easier to push through the pumps when its cold than straight hydraulic fluid is. And it won't push past the seals as easy once its hot. At least, that's my understanding of it.

 

[Gary Fowler]

This sort of reinforces the idea of using Universal Transmission/ hydraulic fluid since so many different brands spec different oils and likely as not, most of the components are pretty much identical.

 

[MossRoad]

I think if engine oil works for the hydraulic system on the Power Tracs, that's what is prudent. Why? Because its available everywhere and no confusing specs to deal with. Has anyone heard from any of the hydraulic systems manufacturers as to what's best?

 

[ponytug]

Just FYI: My 1445 says 10W30 or 10W40.

I would like to offer some information that may help clear up the viscosity issue, since it has come up more than a few times; 5W30 oil must pass both the specification for a 5 weight winter oil (W), and for a 30 weight oil. In common terms, it flows like a 5 weight winter oil when cold, and a 30 weight oil when hot. The standard temperature for measuring viscosity is 212F.

A 10 weight oil is different from a 10W oil, since the latter must meet the specifications for winter (i.e. cold) flow.

Basically moving from a 5W to 15W oil makes no difference at the low temperature end, and a slight difference at the warm end. Moving from a 30 weight to a 50 weight oil almost doubles the high temperature viscosity (12.5 to 21.9cSt). So, moving from 5W30 to 15W30 should have no effect. 5W30 to 15W50 should double the high temperature viscosity, while leaving the low temperature viscosity unaltered. I can confirm that moving from 10W40 to 15W50 had no effect at low temperature, and a modest effect at high temperatures.

Broader ranges, e.g. 5W50, require the use of large amounts of additives, primarily viscosity enhancers, that tend to breakdown over time and shear, reducing the performance of the oil, so these oils may lose viscosity faster than a 15W30 oil, assuming that you only need a 30 weight oil when hot. YMMV...

Finally, in principle a 50 weight oil will take more horsepower to pump due to the increases in viscosity, and it will heat up faster due to the internal resistance. Depending on the pumps and motors, it may deliver more HP by having reduced fluid leakage by the pump and motor seals.

On my PT 1445 neither effect seems grossly observable against the background of variable air temperature and workload.

If you want to know more, there is a nice table at Motor Oil Viscosity Grades Explained in Layman's Terms

All the best,

Peter

 

[Frank Sorbello]

If you drained your hydraulic tank and went to a synthetic oil, would that help with starting in severe cold weather?

 

[KMA]

Oil and hydraulic fluid are hotly contested topics... I started a thread years ago that may address some of your questions:

http://www.tractorbynet.com/forums/power-trac/116623-best-synthetic-hydraulic-fluid-money.html

I went with Rotella T Synthetic 5w-40 due to cost and previous positive experiences with the product. It may help slightly in cold weather starting, but I'm not sure it would be enough to justify the additional expense. IMHO, you would want some other benefits in order to make the switch. Good luck!

 

[RalphVa]

Hydraulic oil is plain 5w5 oil. The 5w30 will be the same as hydraulic oil at low temperatures.

In our commercial dewaxing plants we had big rotary vacuum (on one process) and rotary pressure filters (on another process). Both used commercial hydraulic systems to drive the rotating drum and to provide variable speed. Our mechanics just used multigrade motor oil in them. At that time I worked, it was 10w30. The 5w30s didn't come out until we learned how to make near synthetic and synthetic oils.

Synthetic oils WILL NOT have very many additives mentioned by the person above.

Ralph

 

[ponytug]

Kevin's thread was very informative to me, and helped me think about when to change the oil and what to replace it with. Having decided that viscosity additives have a limited lifetime, I also drained my hydraulic tank and when it was drained, the fluid was significantly less viscous than the 10W40 that had been going in.

Given the lack of difference in low temperature performance between 5W and 15W, I went with Mobile 1 15W50 full synthetic oil (Walmart, on sale). As noted above, 15W is no different at low temperature compared to 5W, but 50 weight oil has some higher temperature viscosity performance advantages in theory.

In practice, the steering is a little stiffer with 15W50 compared to 10W40 when cold, which suggests that specifications may not fully capture actual usage temperatures. :laughing: Otherwise, I can't see any effect. If I were doing it again, I am not sure I would go the synthetic route, but it depends on how well and how long the viscosity holds up. Just for the record, a really cold start for here is 32F, but the PT1445 cranks right over and starts right up. The engine runs Delo 10W40

It was great to see the bottom of the tank and see that it was completely clean. (Hurrah for regular filter changes!) Whether it is worth the cost ($18/gal x 20 gallons) is a personal decision.

All the best,

Peter

Oil and hydraulic fluid are hotly contested topics... I started a thread years ago that may address some of your questions:

http://www.tractorbynet.com/forums/power-trac/116623-best-synthetic-hydraulic-fluid-money.html

I went with Rotella T Synthetic 5w-40 due to cost and previous positive experiences with the product. It may help slightly in cold weather starting, but I'm not sure it would be enough to justify the additional expense. IMHO, you would want some other benefits in order to make the switch. Good luck!