MikeStoke
Army Firefighter
What do you all think? I have heard good things about both.
Mike
Mike

Mike,
Your truck is operated in pretty normal conditions with light loads. Under these conditions there is little to no benefit running synthetic oil.
A synthetic motor oil has two benefits over a dino oil; the ability to withstand greater temperature extremes and extended oil change interval.
Synthetic oil temperature benefits, do not benefit most vehicles since they are not operated in exteme temperature conditions. If a vehicle is routinely operated at 0F and below (think Alaska) then synthetic oil temperature stability is needed. In addition you do not operate in exteme heat environments.
As far as extend OCI, you will not attain it with a 6.0 PSD. The 6.0 PSD, unlike most other diesel engines, is extremely hard on engine oil do to shearing caused by the HPOP (high pressure oil pump) that is used to supply high pressure oil to the oil fired fuel injectors. The recommneded OCI on the 6.0 is 5 - 7.5K. It is rare for anyone running a 6.0 to get much beyond 7.5k before the oil needs to be changed. To date the best performing engine oils in the 6.0 for exteded OCI are Delvac1 and Schaeffer 9000 combined with bypass oil filtration and they only reach 10-12k. Problem is that when you factor in the price increase (3-4x higher) of synthetic motor oil over dino the numbers do not work with the 6.0.
To properly run extended OCI in any engine you must use a premium oil, bypass filtration and perform routine UOA. UOA costs approx. $30-35 per test.
Yes synthetic oils provide lower friction levels, but the numbers are negligible in normal automotive applications. You would be hard pressed to see a 0.5-1 mpg increase using synthetic over dino.
As far as Amsoil & Royal Purple, i would not use Amsoil to lube a bike chain if the oil was given to me for free. Amsoil does not have a "legitimately" API or ACEA CJ-4 HDEO and only 1 CI-4+ and that is the semi-synthetic PCO 15W-40. Don't not believe all of Amsoil's hype, as it is just that hype. Amsoil contrary to there assertion was not the first producer or provider of synthetic motor oils for automobiles. Chevron started it in the 60's and then were followed by NEO, All-proof (now Redline), then Amsoil was forth (they were selling repackaged Hatco synthetic oil btw), followed closely by Mobil1. Amsoils claim to being first with a synthetic motor oil is akin to Al Gore inventing the internet.
Now i do not believe an automobile will seize up and die from running Amsoil, i just am not comfortable doing business with a company that falsely hypes its products and bends the truth to get money out of your wallet.
I have not run Royal Purple, they get good reviews on there gear oils, but i think there are better synthetic engine oils out there. In the diesel engine market Delvac1 & Rotella Synthetic control 98% of the fleet market for synthetic oil.
I ran Redline in my race cars with excellent results but race cars are a special application and we rebuilt the motors between passes.
Now one benefit of synthetic lubricants in your truck would be in the front axle and transfercase. The rear axle uses synthetic from the factory as does the Torqshift transmission.
Just an FYI only use Motorcraft Mercon SP transmissin fluid in the Torqshift, contrary to some manufactures claims no one else makes a legitimately certified replacement oil for the Torqshift. I am a strong believer in synthetic lubricants used in the axles, transfercase and transmission do to the small quanity of oil in these components and the long drain intervals.
Personally if i were you i would stick with a quality API CJ-4 15W-40 dino oil brand of your choice, and if you want to run synthetic then either use Rotella Synthetic or the more expensive Delvac 1, 5W-40.
Most of the new CJ-4 dino oils are made with Group II+ & III base stocks. Rotella Synthetic is made with Group III and Delvac uses Group IV PAO base stocks.
Thank you for your service to our country.
Hahahahhahahahah that one made me laugh out loud. Reps for that.. As much as I hate to do itHere's a pic of the rod-
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