Lower Oil Pressure After Change to Synthetic?

[Techlight]

Hey All,

So I changed my oil to synthetic (6qts of mobile 1, 10-40 with a new filter) and I'm noticing it idles at around 10-15psi when it's warm (possibly a few lower). It's still up around 40psi (where it's always been regardless of oil type) while driving at about 2000rpm.

Is this normal? it used to idle at about 20 or so and the drop has me wondering if it's okay that way.

As reference this is a S & J re-manufactured motor with about 5-6k miles on it. They told me to run the break in oil, then run regular oil for 3000miles and then go to synthetic if I wanted to at that point. I also live in the desert where it's really hot.

Thanks in advance for the input...

 

[Lumpy Grits]

Kinda 'lite' oil for the desert. I run Castrol 20W-50 all year.
It's 103* at my house and you ain't that far from me.
What weight oil did you have in it before?
Are you using the same oil filter brand.
I only use Wix(OEM)oil filters(NAPA).
Why syn oil??
Hope you ain't trust'n a OEM ele oil gauge to give you correct readings.
LG

 

[Torxhead]

I agree with 'Why syn oil" after all it is a tractor motor.

 

[Lumpy Grits]

I agree with 'Why syn oil" after all it is a tractor motor.

Yup, and they were built kinda 'loose' in bearing clearances too.
T'light-Run either Shell 15W-40 Rotella or Castrol 20W-50 dino oil, and that engine will out live YOU.
Get your oil from Wal-Mart and your air-fuel-oil filters & belts from NAPA.
LG

 

[Techlight]

Hey All,

Thanks for the replies...

I guess the reason I wanted to run synth was I figured new advances in oil technology etc etc and blah blah blah. I won't list them because I don't want this thread to turn into a synth/conventional thread lol. At one point I had talked to the guys that reman'd the motor too, but I can't claim to remember what they said haha

I figured it couldn't hurt except for maybe my pocket book, but I really want to take care of the new motor because I really need it to out live me lol. However, I was concerned about the drop in psi in relation to the synth and don't want problems to crop up around that.

As for the weight I was just trying to run what the FSM said to run in it. So I've always run 10/40 in it. [Keep in mind that "always" doesn't apply very well since this is my second oil change and only the third time I've put oil in it]

I'm sure I got that 10/40 recommendation from the guys who built the motor as well as the FSM, although I'm having trouble remembering what weight my break in oil was. But S & J sent that in a box with the motor so I'm pretty sure I didn't screw that one up haha.

I'm laughing too, cause the general consensus seems to be drain the 60 bucks out of it and refill. Do those oil pressures sound too low to run it that way for a while? If so I'll drain it tomorrow, but if not I"d like to get some use out of that oil. As a note I was correct on my lower psi's (8-15), but I was incorrect on the max psi with syn oil, it's running at 35psi fully warmed up on hot days.

In terms of the OEM sending unit accuracy I'm sure it's probably off but it's always ran the same consistently, so I figured I could trust it for the differences when I switched oil at the very least.

 

[Lumpy Grits]

Run what you have.
You did right in using what the engine builder sez to use.
I do hope you are keeping a detailed log on ALL service to the Jeep. Part of that log is list the oil weight used and the amount.
The FSM(MR-252)also sez 20W-50 is OK.
Like I said-Watch for leaks from the engine with M1 in use.
As to waste of $60.00 in oil-Perhaps, if you had made the inquiry on the forum before you bought the M1. Things might have been different.
Don't sweat it---
I would look hard at installing a mechanical oil pressure gauge.
Oil Pressure Gauge. Black Dial, Mechanical Oil Pressure Gauge.

LG

 

[Hedgehog]

I'm a believer in synthetic oil. Why? It's some seriously slippery stuff and mostly it stands up to heat far better than dino oils. Granted it was more or a concerned with the air cooled Harley Davidson Shovelhead than with a water cooled engine. Oil weight can be considered in two categories. The heavy weights that hang around (relatively) making things super slippery and the light weights that move much more quickly through an engine flushing deposits as they go. There is another side to oil though. Along with water, oil acts as a coolant flushing away heat from VERY hot areas of your engine. Faster moving oils tend to flush heat out right along with other deposits.

Oddly enough I run 20-50 in my CJ. The engine is older and I have no idea what has been run before so it is safest to run 20-50 .... Specifically Shawn-Penn racing oil which has all the good old stuff in it that helps older engines.

 

[jdcaples]

<snip>
The engine is older and I have no idea what has been run before so it is safest to run 20-50 .... Specifically Shawn-Penn racing oil which has all the good old stuff in it that helps older engines.

Brad-Penn racing oil? Shawn(Sean?) Penn smacked around Madonna when they were married, I think.

-Jon

 

[Techlight]

I'll probably just run it for awhile and see where it goes. From reading around the net it seems that the drop in oil pressure is normal on the change to synth...supposedly because it moves more efficiently than straight dino. I figure 5-10psi drop is acceptable...

In the meantime I'll call the manufacturer back and see what they say (the thing is still under warranty haha) and I'll look into that mechanical gauge too...

I'm so swamped with little things that need to get done before camping in big bear...right now I'm knee deep in wheel bearings trying to do it in the evening hours btwn work and sleep. I told my son we'd take the Jeep camping this year and dammit I'm gonna make it happen haha (we had to leave it last year so failure is not an option).

LG ...I know I keep saying it, but when I catch a moment I'm gonna hunt you down for that carb adjustment...and bring you a six pack of your choice for all the advice you keep sending my way...

Look for my next post on prevailing torque nuts haha...seriously I need to be schooled.

Thanks again all...

 

[Techlight]

Oh, and I know it's rare haha...but as a side note my AMC 258 i6 / 4.2l don't leak (yet )

Well, except for some thin seepage around that crappy push on oil cap on my aftermarket valve cover (those things suck) ...when I get a spare moment, me and a caliper are gonna stand in the back of the auto parts store and find a threaded oil cap that fits that !

 

[Lumpy Grits]

Oh, and I know it's rare haha...but as a side note my AMC 258 i6 / 4.2l don't leak (yet )

Well, except for some thin seepage around that crappy push on oil cap on my aftermarket valve cover (those things suck) ...when I get a spare moment, me and a caliper are gonna stand in the back of the auto parts store and find a threaded oil cap that fits that !

Clean your PCV valve-That may reduce crankcase psi.
Make sure your crankcase breather is clean and free flowing.
LG

 

[Techlight]

I'll try that...although its done it from day one with new parts. The cap really does suck that badly

 

[Lumpy Grits]

Make sure you have the CORRECT, PCV valve for your engine.
Jeep 6's used a bunch of different ones over the years, and they are NOT interchangeable.
LG