In Reply to: Decision: Go cheapskate or 1st class? posted by Paladin (Bob In PA) on January 04, 2011 at 10:07:43:
The use of specifications like SAE 10W for specefying hydraulic oil is really lame. SAE 10W (if that is what they really mean) is a mon-grade cold weather motor oil and as such has a relatively low viscosity when hot (100C).The ISO system was developed because the SAE specification is extremely motor oil centric and not well suited as a general viscosity grading scheme for industrial oils. The ISO system is a simple measure of kinematic viscosity at 40C - e.g. ISO 32 = 32 cSt@40C, ISO 48 = 48 cSt@40C, ... Most hydrauilic equipment OEM's use the ISO system in their specifciations and and avoid the SAE system.
That said the ISO system, unlike the SAE system, has no mechanism for providing any sort of viscosity index information. You have no way of comparing the temperature behaviors of two different ISO graded oils. With the SAE motor oil scheme you know from the grade that a mono-grade SAE 30 is a low (~100) VI oil and a multi-grade SAE 10W30 is a high (~135) VI oil. That means the SAE 30 is going to get real thick when cooled below freezing while the SAE 10W30 won't.
Most but not all AW hydraulic oils are mineral oils with a VI of roughly 100. That means they will behave like a mono-grade motor oil and get much thicker when cooled below freezing. And that means slow hydraulics. These types of oils are not considered "all-weather" oils. If you are using an ISO 48 in the summer you need to switch to an ISO 32 in the winter if that slow warmup behavior is an issue. If you look around you will find a few so called multi-grade (Ack!!!) AW oils with VI's above 150. Those oils have the stated ISO viscosity grade AND are also good cold weather oils because of thier higher VI.
The universal tractor fluids are very similar to the "multi-grade" AW oils. That is what I would use if the Dexron price tag was to high. Or if you want a motor oil then something like SAE 5W20.
TOH
PS> The diffrence between Dexron III/IV/V.... is not something of concern with a log splitter. The differences are very specific to automatic transmission design. You should be able to use the latest/cheapest/most available Dexron formulation in your splitter.
Posting not permitted in the forum archives.<1294168818">