Re: Why
From an earler post
I have stayed out of the lubricant discussions for a long time. First let me say that I am not a lubricant expert. Second I will say that my dad was. He was a/the industral lubricant marketing engineer at Standard Oil of California (SOCAL/Chevron) for 28 years. He handled all lubricants except for aircraft lubircants. He did everythig from food machinery lubricants, to motor oil.
A quick history of Oil for Diesel engines (for reference see page 105 of "Caterpillar" by Randy Leffingwell). The first Cat Diesels has problems with sticky rings, the problem was worse when the engines were run with the asphalt based oils from the east coast. They ran better when running on the paraffin based oils from the west coast (Standard and Shell). Cat work with Standard Oil ot develope the first detergent oil (Delo). Shell soon followed with Rotella. Th interesting comment in the book is that the drill rings for the oil companies has to use either Standard or Shell products in the Diesels (it did not take them long to develope their own detergent oils). i remember when dad did the introduction of the first multi-viscoity oils to his customers. I also remeber the developement of the first synthetic oils.
The synthetics were developed to handle the problems encountered by the equipement operating on the North Slope. It was so cold that the paraffin in the oil would solidify, so the oil companies deveoped oils without a paraffin base.
My dad thought that synthetics were based used in extreme conditions (hot/cold), and that if the equipment was operating in normal contiditions it was better to spent one's money changing the oil more often rather than using synthetics.
I use Delo in my
L3450. My dad said to use it in everything (cars etc).
As far as the viscosity ratings, you will find that the newer oils cover a wider range (15w-40 vs. 10w-30), it is ok to use an oil with a wider rating. Over time (to keep stocking and manufacturing issues down) you will only find the oil with the wider rating as the older rated ol is phased out.
You can use an oil with a higher service rating. Make sure the first letter is a "C" for diesel and the second letter is equal to or greater than the required rating. When SPI omes out with a new rating they insure that the earler ratings are included. Again this eases the stocking/manufacturing issues.
All the major manufactures relable their oil for other customers (like Sears, NAPA, the car/tractor dealers). The contracts are for several years and the oil company may change from contract to contract, so when you buy a relabled oil you have no way of knowing which oil comapny made it. When I was in high school we used Sears because my dad had their contract, I do not know who has it now.
carl