Has anybody else noticed more noticable engine noise after switching to a full sythetic? Its not terrible but i drive with the windows down all the time and notice some slight ticking at an idle. I think it's because the synthetic is thinner? idk if im right or im about to run into a bigger problem

What did you put in? I run Mobil1 10-30 in mine and it's very quiet.

Royal purple 10w-30

Although i spent 40 bucks on this oil the parts store guy up the street from my house said that its because the oil is so thin... . He told me to try and ignore the sound and/or change to a thicker oil... Also said its kinda scary running a sythetic oil in an older vehicle. No this isn't who i bought the oi from, if it was id be furious

I just switched to Rotella 10w30 and it is a bit louder when cold. I was running Valvoline High mileage full syn in 5w30 and it was not this bad. I was going to go back to the Valvoline next change but now you got me confused.

At idle, that ticking couple be your injectors. Otherwise the 4.0's are common for slight valve tick. Or maybe you have an exhaust leak.

Check out some reviews of Royal Purple motor oil. I thought i heard threw the grapevine that ppl where having engine issues using it. I use AMSoil 10w-40 with extra zinc in my 4.0. whowey recomended it for use in the 4.0 due to the extra zinc content in the oil. absolutely no problems.
15w-40 Rottella in my 214k 4.0
10w-30 Rottella in my 161k 4.0
AMSoil in my 2000 XJ with 137k-used for 40k miles.

I guess this is a good time for a redux of my "how multi-viscosity oil works" post...

An oil that has its viscosity shown as Xw-XX is called a multi-viscosity oil. The number before the w represents the effective viscosity at 0 degrees Fahrenheit. The number after the dash represents the effective viscosity at operating temperatures. In other terms, a 5w-30 oil and a 10w-30 oil have the same effective viscosity at engine operating temps. And at 0 degrees, a 10w-30 will be the same viscosity as a 10w-40.

But in your case... that particular valvoline oil is very low on Zinc and Phosphorous which are extremely important to our 4.0l motors as wear additives.

I've been looking for some oil analysis numbers on RP oils. So far the ones I have found have been SCARY bad for Zn and Ph numbers. If you know of one for the 10w-30 I would be interested.

Well i just got back from playin ball and took a look at my exhaust. I found an exhaust leak, but its behind the cat. Would that casuse the noise? It sounds just like the prob with my mitsubishi.. sticky lifters... but alot of what i've read says that the 4.0's are notorious for louder lifters. Thanks for all the replies

I haven't heard much about Rottela but so far im not liking this royal purple, pretty pissde though it was like 6 a quart

I run Pennzoil platinum in my '97.
Was using Rotella Syn 5-40 in my old Bronco2.
Tried Valvolene Maxlife this time, but notice slight tick as well.

Think i'm gonna just go to RTS 5-40 in EVERYTHING.
They say its even safe for wetclutch motorcycles!

Rotella RULZS!

Rotella is a diesel rated oil. It has plenty of zinc in it to keep your cam happy. Any flat tappet engine should use an oil with a high zinc content. I've broke in 3 engines on rotella and had zero probems with them. Any oil that can go 10,000 miles between changes in an OTR truck is good oil in my book

Is this the rotella T synthetic your talking about that has the zinc? I was looking at the 5w40 they had at autozone yesterday.

Def. gonna check that out. Ok so im gettin pretty pissed now. The noise has subsided but now its randomly missfiring at idle, any ideas?