What the last 2 guys said.
Except I use Delo 400.
I agree with last 3 guys, however i use AMSOIL Full Synthetic 5W-30 Heavy Duty Diesel Oil in conjunction with a Franz oil bypass system. I have used this system for 11 years with my old GQ,GU 4.2 Turbo diesels, D22 Navara and currently with my D40 2.5 manual diesel Navara. Oil is lot more expensive, however oil change intervals is at 20,000 ks. Durring 20,000ks, i use a test kit to check oil every 5,000ks whilst replacing the oil bypass filter. I change main oil filter at 10,000 ks. When changing oil filters i just top up the oil that' required usually half a litre. Even at 20,000ks my oil test results still advise that the oil is Ok.
The reason why i use Amsoil is due to towing a camper trailer and boat up and down beaches and some of the serious tracks my mates and i use on the weekends at Coffs Harbour. Navaras both the 3 lt and 2.5 litre engines producing exsesive heat under load, it is impertive to use an engine oil than can help disapate the heat and maintain engine performance. The following is a bio on Amsoil synthetic oils;
"First of all, let's take a brief look at the history of synthetic motor oil and its introduction to the marketplace. AMSOIL Inc. developed the first synthetic motor oil to meet API service requirements. Lieutenant Colonel Albert J. Amatuzio, President and CEO of AMSOIL Inc. witnessed synthetic lubricants in action as a jet fighter squadron commander. He noted that synthetic oils were developed for (and still are used exclusively in) aircraft jet engines because of their ability to reduce friction and wear on engine parts. This preformance was due to synthetic oil having incredible ability to function dependably at severe hot and cold temps as well as to withstand rigorous and lengthy engine operation without viscosity breakdown. This is critical in aircraft engine operation because, if oil breaks down at 30,000 feet, aircraft engines can fail and ... well, you get the picture. Amatuzio decided that he would develop synthetic motor oil to be used in automobiles for the same benefits. In 1972 AMSOIL introduced the first motor oil for automotive applications. In the early seventies, another company was also working on synthetic oil development for the automobile ... Mobil Oil Company. They came to market with synthetic motor oil in 1975. By the 1990's the other major oil companies added their synthetic oils to the marketplace, in addition to their petroleum-based products.
What are the pros and cons of using synthetic oil in my car?
Pros:
•It flows easier in cold weather, therefore no loss of prime when the oil is cold. Also, it is highly resistant to viscosity breakdown (the ability of the oil to flow easily in all temps) from heat, friction, chemical contaminants.
•Longer change intervals: 7,000 - 9,000 miles between oil changes (compared to 3,000 for regular oil). Some folks have documented up to 25K miles between changes. However, I would not advice going that long!
Cons:
• Cost is twice as much as conventional oil per litre. However it lasts longer, so the actual cost increase is closer to 50 - 60 percent.
•Flows easily, therefore not recommend for use on high mileage engines; nor do I recommend using it in new engines during the break-in period because it is so slippery and dramatically limits the wearing of new mating parts within the engine. This initial wearing of parts is what makes for proper engine break-in, sealing of piston rings, mating of camshafts and lifters, etc.
Does it make my engine last longer?
Yes, because its so slippery, synthetic makes for less engine wear and thus greater engine longevity."
Like anything in life, you must reseach the facts. Eliminate the 80% of bullshit to help obtain the 20% of facts. the 80/20 rule.
Regards RLI