dave1123

I used to work at Valvoline Instant Oil Change and have used their full synthetic since it was introduced. Ashland's full synthetic isn't a TRUE synthetic because it isn't made from scratch without petrochemicals like Mobil #1 is. It is a highly purified petroleum product and therefore is totally compatible with standard grade oils.

I run 10W30 in my 2000 WJ 4.0 for 5K intervals. It is dirty when I change it, but is very clean after changes. This tells me there is no sludge in the motor.

I've used Valvoline oil in all my vehicles since 1962 and never had an oil related problem with any of them. EVEN when my wife burnt up my Chevy truck's 350, it didn't seize. After it cooled down, it started right up. It rattled very badly and only had 10 psi pressure, but I drove it home.

Xj88

2 different engines..
I'm sure running the t6 in my i4 would be OK..

For what its worth the t6 did expose a few leaks in a 4.0 with only 89k on it... most likely just the smaller molecules from the syn though..

Regardless both are great oils

Big David

I've heard that if you swap to syn. you can develop oil leaks due to it being a thinner oil. ESP in high mileage motors. The good thing is you can go twice as long between oil changes.

Not sure if it's true. Worth a shot.

I'm going to Rotella & back with the WIX filter this w/e.
BTW, the WIX is only .22 cents more than the SHAM filter.

Xj88

Leaks can show up because the oil molecules are smaller with synthetic

RaiderMike67

There are a million different opinions on syn vs. conven. and most of them are wrong.

The most important thing you can do for your motor is keep the oil changed to extend life, the type of oil you choose is your choice synthetics do tend to last longer so less oil changes are nice. I buy whatever is on sale at Oreilly with a filter and stock up, I'm not brand loyal right now I have a few gallons of Rotella T.

Turbocube

I'm about to get an oil change for my XJ sometime next week. I don't even know what's in it right now but I'm wanting something very good for the engine. It has 137K miles and I'm fairly certain it has not been using synthetic for any of those. Would it be a bad idea to get 10w40 Valvoline synthetic put in it?

EDIT: I just now realized that I've resurrected an ancient thread. I apologize if this is frowned upon in the community.

Xj88

What kinda climate are you in?
I'd just say go Mobil 1 10w 30

karl4x4

Doing the switch is a great Idea. I have been selling and using Amsoil for a little over 20 years now and Its done me and my customer very good. My jeep as reached 513 000 km and now I put the engine in a newer body.

some people say: once you have synthetic you can not put conventional oil in it. That is not true.
You can put any regular engine oil (proper grade of course) in your engine after having synthetic. What this will do to your oil is just degrade its quality to whatever type of oil you just added.
Mobil1 is also very good.

Using synthetic allows you to use a finer filter therefore remove smaller particles. Also look up their Nanofiber air filter video. very impressive

One thing to be careful with. and that includes all oils used on flat tappet cam engines. Newer oils have a reduced zinc content. Amzoil came to the rescue. Read the link.

http://www.amsoil.com/techservicesbu...t%20tappet.pdf

Amsoil.com can tell you exactly what is recommended, how much oil even what torque your plug needs to be. Its a great site.

I could go on and on. Needles to say, I've done many many trials and test and research on the subject. I should be able to answer any questions if you have any...

Turbocube

Florida. So, wet and hot most of the time, and 60 degrees is "freezing."

Wow, that's really impressive.

RaiderMike67

Funny every time there is a thread on oil someone selling Amzoil pop's up! It's all good, Amzoil sells a great product, buy it by the case and you can get it for about the same prices as most major higher end synthetics.

I've heard more then one story of guys getting over 500,000 using amzoil exclusively, I had one guy tell me with the best filters they make that he went 100,000 miles between oil changes...I'd never recommend this but he swore to it.

dave1123

I bought my 67 Camaro new and Chevy's recommended oil changes were 4000 miles and a filter change every 8000! That's just plain crazy!! Why would you run clean oil thru a dirty filter? What sense does that make? 67 was the last year for the old metal can filter. They went to a spin-on after that. Changing those old cans was messy and you had to wash it out to put the new filter in. Thank you whoever invented the spin-on!

karl4x4

Higher end synthetics? Very few other oils has met or exceeded Amsoil's products. I've used Mobil1 for a few years cause of cost but never veered away from their filters. Their quality has been met by few but exceeded by none. Not to mention the new nanofiber technology air filters.
All the years I sold the stuff I never made a dime off it. I always sold at cost and only charged for the oil changes. Now, retired the business and buy it for self and friends only.
I did switch to Amsoil Zrod oil for its higher zinc content. Newer oils are mandated by government to cut zinc content in half for environment and cat longitivity. It's ok for roller lifters but murder on flat lifter cams like our loved 4.0L
PS. None of the above is oppinion. It's all backed facts.

dave1123

I've heard this before, but I don't believe one word of it. Flat tappet valve trains don't need zinc to wear better. Only heavy spring pressures cause premature tappet and cam wear. GM had a problem with soft cams in the late 60's, but they worked that out. If you want added lubrication for break-in, use Moly D.

RaiderMike67

Higher end synthetics? >>>>>>>

I should have phrased this as "popular name brands" such as Castrol or Pennzoil, there is no real comparison in quality. Amzoil and Royal Purple are high end synthetics.

dave1123

I feel like starting another science class. Did you know that 90% of bearing wear occures during start up before there is oil pressure? ANY oil that supports an oil film at pressure between the crank and bearings will work. The question you have to ask yourself is will this oil hold this oil film at higher cylinder pressures and engine temperatures? Also will it do an adaquate job lubricating thing that are splash lubed like pistons and valve stems?

The debate will go on and on about one oil or the other until the world ends without one clear cut winner. What ever works for you is the answer.

Damn! I feel like Socrates!