Differences Between Types of Oil

A they are often different materials. A lubricating oil is needed in a gearbox type transmission. In an automatic transmission you need a non lubricating fluid to enable the clutches to work.

For hydraulic systems you need a fluid that is close to motor oil, with few additives.

http://en.wikipedia.org/wiki/Hydraulic_fluid

when the term 'oil' is used, the inference is that it comes from crude oil. In fact the many fluids used for transmissions are not directly distilled from crude, but may use feed stocks from oil after various chemical processes that mean they are not longer an oil.

the term "transmission fluid" is preferable

'Oil' is not an adequately descriptive term when referring to 'lubricants'. For instance, there are water based hydraulic fluids--widely used in mining because it will not catch fire and burn. Gear lubricants are formulated with additives required to protect the gear teeth from damage, and the additive type is dictated by loads, gear materials, relative gear tooth movement, temperature, presence of moisture, start-stop operation, ambient temperature,etc.

'transmission' is also very imprecise. For instance, automotive automatic transmissions require vastly different lubricants and additives than heavy duty off-road manual transmissions.

In summary, lubricants and hydraulic fluids are carefully formulated to function in the specific application.

there are indeed special niches where water based hydraulic fluids are used. There are also synthetic hydraulic fluids, motor oils, transmission fluids and brake fluids(a hydraulic fluid too).

In general motor oils and hydraulic oils bother derive from crude oil via distillation.

Over time since the 1900's they have diverged as additives have been added to extend their working life and to function at high temperatures in cars. Hydraulic fluids have also diverged from oil as special applications require diferent attributes.

Many new cars now have fully synthetic brake fluids and automatic transmission fluids. Many cars cannot tolerate anything but their own optimised transmission fluid due to friction, seal and temperature needs.

Smart people switch from crude based oil to full synthetic after the initial run in period = very long engine life.

What's going on here?? My '92 Ford T-Bird specifies ATF for the 5-speed manual transmission. There are no hydraulic lines or clutch plates. Ford put in the T-Bird an F-150 pickup manual 5-speed transmission with slightly different synchromesh design for smoother shifting. Why is ATF specified. Why not Mobil-1 synthetic oil?

I put in Mobil-1 ATF. Does the different synchromesh design require mineral-oil-based ATF for proper operation?? I've tried (with no success) to contact Mobil re the difference between Mobil-1 ATF and regular Mobil-1. This car has 171,000 miles on it and runs fine (except 2nd-gear synchro is out and requires "double-clutching").

The biggest difference between transmission fluid and other types of hydraulic oil is the amount of detergent. Detergents in fluids help prevent the formation of precipitates and sludge that can gum up valving and coat moving parts. My company manufactures hydraulic lifting equipment. We are currently using a hydraulic oil from Petro-Canada that is what they call a group 2 product. Group 1 products are the old stand by base stock oils that are produced through the traditionally used refining methods from crude oil. Group 2 oils are made by severely hydro treating and hydro cracking processes that produce oils that are very pure. They have better viscosity index numbers which means that they maintain their viscosity better across a broad temperature range. Group 3 oils are synthetic. Many of the specialty fluids like brake fluid and some transmission fluids come from the group 3 category. The most common types of transmission fluid are compatible with the rubber, Viton, and polyurethane seals common in most hydraulic equipment. The extra detergent does tend to make seals swell a little more some what reducing seal life. They are also a little more expensive so if you do not require the specific performance characteristics of the product you opt for the more cost effective options that meets the performance requirements. I would recommend a good quality group 2 product. Conoco Hydroclear, Chevron Rykon, and Petro Canada Hydrex are all good choices in the ISO weight that meets your temperature and viscosity requirements.

Maximum Pressures is also a big consideration. Hydraulic oil can easily work in the 3500 PSI to 5000 PSI for regular grade and higher pressures for other grades. Transmission oils generally work in 1000 to 1200 PSI Range, maybe up to 1500psi.

Many of our customers use tranny oil in their truck systems because the 12V hydraulic pumps call for it in their manual. Transmission oil is fine for the pump, but the cylinders tend to fail early and wear more if they are used at pressures higher than 1500psi. These pumps are good to 3000 psi so failure is common.

I can tell if system uses transmission oil by one glance at the cylinder rod. It is supposed to be smooth and shiny chrome (very high gloss). I will look dull and have very fine scratches.The inside will look the same and the O-rings will look a little ragged. This is because the transmission oil cannot take the pressures and does not lubricate and protect any of the wear surfaces .

Transmision oil is much cheaper and easier to find. It has some type of friction additives for transmission use.

Cylinders that use Hydraulics oils will look great for decades (seriously) as long as there is a 10 micron or less filter in the sytem that is changed regulary.

If you can guarantee that you can keep your Maxium pressure below 1200psi it will fine. But consider the cost of replacing your cylinder due to wear vs the cost for the oil.

I m an engineering student in 4th year and want to know the what is the temperature inside the muffler and while leaving exhaust gas to the atmosphere what will be temperature.. thanking you

Prasenjeet (Dr.MGR.Educational & Research Institute, Chennai)

If the temperature falls below 135degC then there is a risk of sulphuric acid condensing, the effect of which will be to start to rot the components. 135degC is a frequently-specified minimum stack exit temperature in chimneys.