I started off using Rotella Syn in all my cummins and thought it was great. Then I changed over to Amsoil and didn't notice any real difference and used it for about 20k miles. Then, about 17k miles ago, I switched to Royal purple and WOW, what a difference. It made my truck run so much smoother and Idle so much better, that I switched the entire truck to RP Synthetic. Unbelievble. Anyone else experience this?

 

I Found It To Be Just The Other Way.i Was Very Dissapointed In The Royal Purple So I Changed To Amsoil Engine Noise Is Gone And Mpg Increased By 1

 

I've used RP the entire life of my truck and I truly love the stuff. It stays slick, and ready for more after 15k miles. I use it in all my applications when i can afford it. Good product, comparable to Amsoil.

 

Are you guys sure that RP is an extended drain synthetic, like Asmoi?

 

Yes RP is extended drain, comparable to Amsoil.

 

If anyone out there wants to know the difference between Amsoils and Royal Purple's competitive test, call each company and talk with their techs. Don't let the company know that you are or have talked with the other. Ask them to explain their test and who performs their test. If they do it themselves or if they have an independent test facility do it. Then ask them about their thoughts on each other. I was very surprised with what I was told. One company kind of dug a hole and buried themselves in it when I was on the phone with them. I was amazed. I won't say who and don't get me wrong, each company makes an excellent oil. The one just makes claims about the other that isn't true at all, but the way it is worded is very confusing and very deceiving. Find out for yourself.

 

My truck is on Amsoil - bumper to bumper - couldn't be happier. I also run their bypass filter and air filter, both doing a real nice job, oil samples are the best they had ever been since switching over to Amsoil and the bypass.

 

This will ruffle a lot of feathers, the only difference between synthetic oils is the amount of money leaving your billfold. I have used synthetics for 25+ years and have done oil testing for as many years and can see no difference between them. The bypass filter will make any oil look good in an oil sample.

 

ive used amsoil for a while and it worked good then i switched to royal purple and got better mpg, but rp didnt last that long

 

I have worked in Prudhoe Bay Alaska testing every oil imaginable. Temps all the way down to -90 zero. In and out of car testing. Synthetic is the way to go. The colder it gets, the better they work. And I'm not just talking about temp lubricity. Additives and compounds hold up 10 times better than any non-synthetic. Test don't lie.

 

According to this:
http://www.amsoil.com/products/gearl...hitePaper.aspx

Amsoil's test was done in an independent facility..
I run Amsoil and love it.
Scott

 

Just about to point these fellers in that direction. Made a believer out of me.

Paul

 

Might want to reasearch that company a bit more fellas..

Oh by the way ever wonder why there is no API seal on Amsoil full syn?

 

No API seal is because that seal cost a TON of green to get.Differance between Royal Purple and Amsoil in a seat of the pants feel is zilch.If you think it idles smoother etc.thats ok,be happy!

 

Trust me, I've done my research, A TON of research, actually. And the poster below you is correct, Amsoil does not have an API rating on their full synthetic simply because it costs a CRAP LOAD of money to get. IMHO, Amsoil products speak for themselves. Use what you like, like what you use, but I'll keep using Amsoil.
Scott