Hello

I recently had my mechanic tune my valves. He said that I should be using a heavier oil, 10-W 40. The owners manual for my XJ says that 10-30 is good. Should I be running 10-40 in my XJ for the summer?

year? miles? etc...

Hello

I recently had my mechanic tune my valves. He said that I should be using a heavier oil, 10-W 40. The owners manual for my XJ says that 10-30 is good. Should I be running 10-40 in my XJ for the summer?

In the summer time, why not run 10W40? The owners manual gives you an oil that is good for year round performance. If you are only going to run this oil through the summer, 40 or even 50 is fine. Just remember to put 30 back in before winter.
Read these. They explain multigrade oils.
http://engineoil.blogspot.com/2006/07/5w40-10w40-10w50-and.html
http://photos1.blogger.com/blogger/111/2738/1600/coldtemp.gif

Yup...more range in a multi-grade oil in an older engine will help when it is hot or on long extended driving.

I use a 5w-50 Castrol Synthetic in my 97 4.0L with a larger filter. So I have basically 7 quarts in there. Oil pressure is 40-60 unless it get really "hot". The 40 is at idle.

Tuning your valves???? You have a solid lifter engine?

This is all my opinion.

I have read the added extender package used in 10w40 oil to create the wider range of viscosity can cause problems. Many car makers say specifically not to use 10w40.....typically it's 5w or 10w30. Modern engines have much tigher tolerances and higher flow oil pumps. The lighter weight oils provide faster circulation to areas in the upper cylinder head to help reduce wear

Did your mechanic give you a reason for using 10W40? Is your oil pressure running low? Unless there is some "problem" (like trying to get a another 5 to 10K out of the engine before you rebuild it) I would stick with what the factory recommends.

Mike
00XJ

Most of the modern vehicles, like my Mazda Tribute recommend 5w-20 to get the EPA mileage and the actual gas mileage up. Even the new Toyotas will go to the 5w-20 spec.

Now, I think this is much too thin for an "ancient" pushrod engine like the now discontinued 4.0 liter.

Most of older pushrod engine that don't tach up to 6000 rpm or higher can use a thicker oil, especially if there is piston slap noises that you may not enjoy hearing.

I use a thicker oil here in California, because usually it won't freeze after Feburary. We also have the great super highways where Porsches and BMW 7 series cars are clocking past you doing 90 mph. So, the four liter has to run at about 3500 rpm for hours on end. My last trip to the Jeep Jamboree was a 1000 mile plus round trip, mostly at 80 mph. I run seven quarts of 5w-50 Castrol synthetic in there with a 1.5 quart filter.

BTW, I bought this Jeep new and have run 10-40 in it most of the time (they didn't make 5w-50 back then). 10 years and 139,000 later and nope no engine failure due to the oil. Even when my daughter had it in college and drove it all over LA at high speed and I had no time to be changing the oil. I even had the oil changed at the dealer and had them put whatever in it. Go figure.

So, in conclusion, the weight oil you use is determined by the type of driving that you do and the temperature of the climate where you will be using your Jeep. The most important thing is a good quality brand. Synthetic is excellent but sells for almost $5.50 a quart. High end manufacturers use synthetic from the factory.

EDIT: check this link http://www.castrol.com/castrol/genericarticle.do?categoryId=82915470&contentId=6006933
or....http://www.castrol.com/liveassets/bp_internet/castrol/castrol_usa/STAGING/local_assets/downloads/p,q/pds_syntec_usa.pdf
or....http://www.synerlec.com/prodsa/rpro.html

Aloha....

Agree with your philosophy....if it ain't broke don't fix it.

I think you're confusing "ancient" with "heritage" or maybe "lineage" (as in long)....besides I think inline sixes are kinda cool in an antideluvian sort of way.
For an American inline six, it was pretty up-to-date for it's time and in fact AMC and DC did improve its performance in many areas. The last great American inline six was the Pontiac OHC six built back in the late 60's.

What does oil viscosity have to do with piston slap?.....I've always thought that came from worn out cylinders and/or pistons....or owning a late 90's or early 2000 GM pickup with certain V8's...in which case that would be "normal". If your rod bearings are knocking then a little thicker dose of motor honey will help stave off the inevitable for awhile.

What kind of oil filter setup are you using? Other than caring for the oil needs of an engine the next best thing is to have more of it....so what's your setup?

Later....
Mike
00XJ

LOL....just joking about the "ancient" and yes, it is truly a "classic" engine design for american engineering. But more for its durablility. Yes, because of its long run, it was improved upon quite a bit.

Yes, a little piston noise from the 4.0L is "normal", but a little heavier oil will keep the noise down a bit more.

The large oil filter is a Fram PH977A. For those that don't like Fram, you can use a WIX 51773 or a Motorcraft (Ford) FL299. (Funny, some people just don't like Fram, but they do sell a lot of stuff.)

BTW...I think I will be using the Castrol Sythec 5W-40 in the fall. I just think 30 weight is too thin for my taste, IMHO. I have always used 10-40, until I saw the 5w-50. But, like I said, I will be switching to the 5w-40 when it cools down.

The large oil filter is a Fram PH977A. For those that don't like Fram, you can use a WIX 51773 or a Motorcraft (Ford) FL299. (Funny, some people just don't like Fram, but they do sell a lot of stuff.)


So these filters just screw on using the normal filter mount.....very cool....and they add about a quart and a half to the total?

Fram....yeah, they used to be good stuff but I had heard they are put together like crap inside....thought it was just a lot of hooha 'til I was directed to this website....makes for some interesting reading...

http://people.msoe.edu/~yoderw/oilfilterstudy/oilfilterstudy.html

Lotta folks buy 'em because they are cheap and available at WallyWorld and other fine stores.

Yeah, they just screw on. Add about one quart. I must say I have a late model, so I don't know if it fits all models, because I know they changed the mount and the starter from some early designs.

I might look for another brand in the future. Yes, I know the parts for Wally's are lesser quality, but they are made to a cheaper spec just for Wally. All the brands there are made to a different spec to keep costs down. (Well, most brands, you have to be the judge.)

"Yes, a little piston noise from the 4.0L is "normal", but a little heavier oil will keep the noise down a bit more."

is a little piston slap (knocking sound from under engine- I think it is piston slap) normal in the sense that it is not worth fixing on a motor this old? or is it just something that is natural for the Inline 6?

is a little piston slap (knocking sound from under engine- I think it is piston slap) normal in the sense that it is not worth fixing on a motor this old? or is it just something that is natural for the Inline 6?[/QUOTE]

"Piston slap" typically occurs when the piston does not move up and down in the cylinder without rocking back and forth in the cylinder bore....the rocking action of the piston creates the "slap" against the block. On some engines, due to the metallurgy of the piston, you will get a little piston slap on a cold engine that will go away as the engine warms. I have a '98 GMC with a 5.0L (305) V8 that will slap a piston on a cold start-up....as the engine warms it goes away. If piston metallurgy is not a factor, it simply means the engine is wearing out and eventually will need a rebuild.

Noises down low in the engine are typically main bearing or rod knocks....they will often be the loudest when the engine is cold started and fade or reduce as the oil circulates and builds pressure. You can do a temporary "fix" on this by using thicker or heavier weight oil (STP, Motor Honey etc can also help) but eventually the bearing(s) will wear to the point they can no longer keep the oil pressure up (especially at idle).

If there is only one rod or piston making noise you can isolate it by disconnecting the plug wire, one at a time, from each cylinder....and listening to see if the noise/knock/slap goes away or is greatly reduced.

Engine noises due to wear are a normal part of aging on any engine....the inline six is no different. You may hear some soft valve train clatter which is generally not anything to worry about. Knocks and slaps are typically indicative of an engine wearing out....and they are inevitable.

Hope this helps....

Mike
00XJ