Ask the Expert ...about Oils
Select a question from one of the three categories below (engine oils, hydraulic oils & transmission/final drive oils) to view the expert's answer.
Engine Oils
Hydraulic Oils
Transmission/Final Drive Oils
Can I use the new CI-4 rated oils in my diesel engine?
If your engine calls for an oil that ends with "-4" such as CG-4 you can use the CI-4 oil without concern over a negative impact on your diesel engine. The three main tests for the CI-4 oil are more severe than for the previous oils but the oil is backwards compatible with earlier -4 oils.
What does the API designation on my engine oil mean?
The API (American Petroleum Institute) service symbol and certification mark identifies quality engine oils for gasoline and diesel powered vehicles. Oils displaying the API marks meet performance requirements set by U.S. and international vehicle and engine manufactures and the lubricants industry.
DIESEL ENGINE OIL CATEGORIES
Oils designed for diesel engines fall under API's "C" category. Look for performance levels such as CH-4, CG-4, and CF-2.
GASOLINE ENGINE CATEGORIES
Oils designed for gasoline engine service fall under API's "C" category. Look for performance levels such as SJ or SH.
What are the API Oil Categories?
| Diesel Engines |
| CH-4 |
Current |
Introduced December 1998. For high speed Four stroke engines designed to meet 1998 Exhaust emission standards. For use with fuels With sulfur content up to 0.5% weight. Can be used in place of CD, CE, CF-4, and CG-4 oils. |
| CG-4 |
Current |
Introduced in 1995. For severe duty high Speed 4 stroke engines using fuel less than 0.5% sulfur weight. For engines meeting 1994 emission standards. Can be used in place of CD, CE, and CF-4 oils. |
| CF-4 |
Current |
Introduced in 1990. For 4 stroke naturally aspirated and turbo charged engines. Can Be used in place of CD and CD oils. |
| CF-2 |
Current |
Introduced in 1994. For severe duty two Stroke engines. Can be used in place of CD-2 oils. |
| CF |
Current |
Introduced in 1994. For off road engines Including those using fuel with over 0.5%. Sulfur. Can be used in place of CD oils. |
| CE |
Obsolete |
Introduced in 1987. For four stroke high speed Engines. Can be used in place of CC and CD oils. |
| CD-2 |
Obsolete |
Introduced in 1987. For two stroke engines. |
| CD |
Obsolete |
Introduced in 1955. For certain naturally aspirated And turbo charged engines. |
| CC |
Obsolete |
For engines introduced in 1961. |
| CB |
Obsolete |
For moderate duty engines 1949 to 1960. |
| CA |
Obsolete |
For light duty engines 1940's and 1950's. |
| Gasoline Engines |
| SJ |
Current |
For all automotive engines presently in use. Introduced in the API service symbol in 1996. |
| SH |
Obsolete |
For model year 1996 and older engines. |
| SG |
Obsolete |
For model year 1993 and older engines. |
| SF |
Obsolete |
For model year 1988 and older engines. |
| SE |
Obsolete |
For model year 1979 and older engines. |
| SD |
Obsolete |
For model year 1971 and older engines. |
| SC |
Obsolete |
For model year 1967 and older engines. |
| SB |
Obsolete |
For older engines. Use only when specified by the manufacturer. |
| SA |
Obsolete |
For older engines. No performance requirements. |
What is the difference between the current CH-4 oil and previous oils?
The API CH-4 oils were developed to meet the needs of the new high performance diesel engines including the low emission engines. These oils will exceed the performance of the previous CG-4 oils in the areas of deposits on pistons, control of oil consumption, wear on piston rings, valve train wear, viscosity control, and corrosion.
Three new engine tests were developed for the CH-4 oil. The first test specifically evaluates deposits on pistons for engines with the two piece steel piston. This piston deposit test also evaluates the control of oil consumption. A second test measures the wear on piston rings, wear on cylinder liners, and resistance to corrosion. A third new test measures the wear on the valve train, the resistance of the oil to plug the filter, and the control of sludge--all under high soot conditions.
In addition these CH-4 oils have tougher limits for viscosity control in applications that generate high soot and have improved oxidation resistance. CH-4 oils must pass an additional test for piston deposit control in engines that use single piece aluminum pistons. Oil performance is also established for engines that operate in areas with high sulfur diesel fuel.
As a result CH-4 oils are recommended for use in extended drain intervals that demand the use of premium oil.
Is oil containing re-refined base stocks acceptable?
Oils containing re-refined base stocks are acceptable for use in Caterpillar engines if they meet the specified performance requirements. The re-refined base stock oils can be used exclusively in finished oil of in combination with new base stock oil. The process that is used to produce the re-refined base stock oil generally involves vacuum distillation and hydrotreating of the used oil.
Filtering is inadequate for the production of high quality base stocks.
Can I mix oils from different manufacturers?
Oils from different suppliers can be mixed as long as they are the same types. Do not mix engine oils of different types such as ISO hydraulic oils or gear oils. One point to remember is that your IR results on your oil analysis is based on referencing specific new oils and will be inaccurate if oil types or brands are mixed.
Can I mix oils of different viscosity?
Yes you can. As an example a 10W30 can be mixed with a 15W40. The resulting viscosity will be somewhere in between the two products being mixed. Nevertheless, mixing oils of different viscosities is not a recommended practice as you will have no point of reference for lab testing.
Are some oils better than others?
As an oil analysis facility we make oil recommendations by specification, API performance rating, and viscosity grade without recommending one brand over another. We are in no position to test the "quality" of any given oil -- only its basis characteristics such as viscosity, TBN or TAN.
Can I use engine oil in the transmission or final drives of my Cat machine?
For years the Caterpillar recommendation for power train components was engine oil. This changed a number of years ago as materials changed and loading increased.
In transmissions the new clutch materials are sensitive to nitrogen compounds and unfortunately many engine oils have these chemicals in their additive packages. In addition the new engine oil formulations are designed to reduce friction as much as possible whereas the clutches and discs in the power shift transmission depends on controlled friction for a rapid lock up. The use of engine oil can result in slippage during the engaging process. This can result in high localized heating on the faces with shortened clutch life as a result. The recommended TO-4 oil for use in transmissions has no nitrogen compounds and is totally compatible with all transmission materials. In addition it is formulated to provide controlled friction and rapid clutch lock up to reduce localized heating and to extend clutch life.
The oils now recommended for transmissions and final drives have an enhanced load carrying ability to protect gears and bearings. The specialized TO-4 oils recommended for these applications can be formulated to provide these characteristics, as they do not have the restraints of being able to function in an internal combustion engine.
As a result of these facto the use of engine oils in these applications is no longer recommended.
What are the Engine Manufacturers Association oil ratings?
The Engine Manufacturers Association (EMA) has developed lubricant recommendations as an alternative to the API oil classification system. LRG-1 is a recommended guideline that defines a level of oil performance for high speed, four stroke, heavy and light duty diesel engines. LRG-1 oils may be used in Caterpillar engines where API CH-4, CG-4, and CF-4 is recommended.
The tests and the test limits that are used to define LRG-1 are similar to those of the API CH-4 classification. LRG-1 oils are designed to control the harmful effects of soot with improved wear resistance and improved resistance to oil filter plugging. These oils will also provide superior piston deposit control for engines with either two piece steel pistons of aluminum pistons.
Can I use engine oil in my hydraulic system?
Engine oil makes excellent hydraulic oil for use in Caterpillar machines. In fact Caterpillar and Sure Craft 10W hydraulic oils are re brands of engine oil. When selecting the viscosity of the engine oil, which you are going to use as a hydraulic oil, you should consider your start up temperature as well as the regular daytime ambient temperature.
Can I use diesel engine oil in my gasoline engines?
Many diesel engine oils also have an API rating for gasoline engine use. Consult the spec sheet from your oil supplier or the API information on the container. (See API classifications in this section)
Can I mix engine oil (or engine oil that is re branded as hydraulic oil) and ISO type industrial hydraulic oil?
Mixing oil types such as these is not a recommended practice as the chemistry of the additive packages is quite different. If the additives are not compatible they will precipitate out and will coat and plug the return line filter. This additive precipitation problem may or may not occur but it is not worth the risk.
How do I know if the hydraulic oil is a re branded engine oil?
Typically re branded engine oils retain the SAE viscosity grade as part of their product name. Typically you would expect to see such an oil named xxxxxx10W. The 10W represents the SAE viscosity.
How do I recognize an ISO industrial hydraulic oil?
These types of oil carry the ISO viscosity rating and can be recognized by numbers such as 15, 22, 32, 46, or 68 after the product name. The number represents the oil viscosity in centistokes at 40 degrees C.
Why does Caterpillar recommend the use of engine oil (or engine oil re brands) as hydraulic oil?
Typically engine oils contain a significant amount of zinc as an anti scuff agent to protect the engine camshafts. This zinc additive acts to protect the hydraulic pumps in shock load conditions. While industrial type hydraulic oils often contain zinc the concentration is not as great as is found in engine oils.
Can I use industrial type oils in my hydraulic system?
Caterpillar will allow the use of industrial type hydraulic oils as long as they contain either 900-ppm of zinc (which is unlikely) or have passed the Vickers 35VQ vane pump test. Caterpillar warns that less than optimum pump life may result from the use of these oils.
What is the recommended cleanliness level for hydraulic oil?
Contamination is the cause of the vast majority of premature hydraulic failure and is responsible for most premature wear. Most mobile machines require an ISO cleanliness level of 18/15 to assure optimum life of components.
What oil can I use in the Hydrostatic transmission in my Bobcat?
This depends on the age of the machine. Some machines use regular automotive automatic transmission fluid (Red Oil). Other machines use an ISO 32 Hydraulic oil (Not Red).
Why are TO-4 oils recommended for my transmission and final drives on most Cat machines?
TO-4 oils have more load carrying ability than engine oils to protect heavily loaded gears and bearings in these compartments. In addition they also provide controlled friction to assure quick lock up of clutches and discs in power shift transmissions. This reduces heat and wear. Finally they contain no nitrogen products and are completely compatible with all transmission materials.
What oil should I use if I operate in very cold conditions?
If machines are subject to cold starts in temperatures below minus 20 a 10 weight TO-4 oil may not be suitable. In this case the next best choice would be a multi grade oil such as a 0W20 containing the TO-4 additive package. Finning Sure Craft Low Temperature Transmission Oil would be an example. This will allow cold temperature starts to -40 degrees C.
How clean should I keep my transmission fluids?
Regular power shift transmissions with require an oil cleanliness level of ISO 21/17. This equates to an LPD reading (15 microns) on the SOS reports of 1300 particles.
Newer electric hydraulic power shifts need even cleaner fluid and require an ISO cleanliness level of 18/15. This would equal an LPD reading of 320 particles.
What is the cleanliness level for my final drive fluid?
Excluding large mining equipment the general cleanliness targets are as follows:
| Excavators (only 300 series) |
| 0 -30,000 particles |
normal |
| 30,000 - 50,000 particles |
borderline |
| 50,000 plus particles |
action required |
| Most Other Machines |
| 0-12,000 particles |
normal |
| 12,000 - 25,000 particles |
borderline |
| 25,000 plus particles |
action required |
| Grader Tandem Drives |
| 0 -30,000 particles |
normal |
| 30,000 - 50,000 particles |
borderline |
| 50,000 plus particles |
action required |