15 w 40 is it ok to use

I plan on using 15 w 40 on my next oil change, any disadvantages?
It's a new motor, 1200 mi, have been using SAE 30 with additives (+zinc)during this past summer. Oil pressure has been good, 18 psi, hot idle, in gear
thanks
Bruce

 

whats the cruise pressure, and high rpm pressure with current oil ?

 

40 lbs at 1500 rpm at 55 mph. 190 deg F.
high RPM 65 lbs, (3800 rpm) that's currently where it shifts at WOT
thanks Bruce

 

The only thing to watch is the high RPM pressure, but I don't think you will be close to anything that would cause concern.

In all likelyhood, you may see a 5psi increase across the board. It will be interesting to see ... please post the resulting pressures once done.

... and KEEP using zinc additive unless running one of the specialty brands/blends made specifically for our flat tappet motors that contain thier own ZDDP packages

 

Hi Bruce;

Ive been using 20W50 which recently changed to 15W50 by Mobil 1 for a long time. Ive been using it as a bandaid because of my shot bearings.

Although in our circle of freinds there are a few rebuilt engines with verified good bearing clearances and we all use 15W50. The main reason is we abuse these cars, an in the middle of summer the 50 of the 15W50 makes me feel better.


So in short, it wont hurt anything, but if youre just putting around or cruising, you want to use the thinnest oil you can get good pressure with.

In my experience, when you put in new oil, for about a week the pressure will be high at startup. But when the oil breaks in a bit the pressure goes back down to normal. Once the engine is warm (in my experience) the pressure is the same regardless of the weight used.

 

multigrade oil is only as thick as the first # and protects as the second # so straight 30 or sae 30 is thicker than 20w50. using diesel oil with flat tappetts is good no additive necessary..

 

Just remember the lower the first number the thinner the oil is when cold, therefore the quicker you get fresh oil to the bearings and lifters after a cold start. Like Azeem says run the lowest viscosity oil that gives good oil pressure.

 

Ive used Delo 400 (15-40) in everything I own for 25 years. Work car has 310,000 miles with the original untouched engine. Ive driven this car for almost 20 years In 0 -110 degree weather. Never had any problems with it. I also use it in my dragster engine for "break in oil" then it gets Mobile 1 10-30 after the 1st weekend out after a rebuild (1000hp). Ive used this in dozens of cars, lawnmowers and generators and everything in between.

 

If you have good pressure with 30w why do you want to change?

 

For cold start ups, I'd still like to drive the car for a few weeks, but it gets down to 32 deg F in the mornings.

There's no chance of wiping out the front cam bearing or putting to much pressure on the oil pump gear?

thanks Bruce

 

I use a mix of 15-50 and 10-30 Mobile 1, I use a 50-50 mix on this. I get 15-20 lbs at idle in gear and 70 lbs at 6 grand.

 

i use 10w30 castrol gtx + zddp. i run 40 lbs at 2000 rpm. your oil pressure, currently, is excellent as is. no need to increase the base viscosities.

 

thanks for the replys,

with the current SAE 30 there no chance of doing damage at low ambiant temperatures on start up? (32 deg F and lower)

thanks
Bruce

 

Go with synthetic oil if you have cold weather. I run 10W30 synthetic oil in all my vehicles and they all start well at even as low as -32 F. If you take a bottle of regular oil and put it in the freezer along with a bottle of synthetic oil you will see that the next day the synthetic oil is still fluid and the regular oil is stiff.

 

Rod I was under the impression that the diesel oils were cutting their zinc content. I have been using Rotella 15/40 for years but was considering switching to straight sae 30 with a zddp additive. I just used up the last of my early Rotella 15/40

Bob H.

 

I never even considered synthetic, do I need to put ZDDP with it?
thanks Bruce

 

Yes, I still use the ZDDP with the Synthetic. Just watch for oil leaks as sometimes Synthetic leaks through where conventional oil does not. Worst case, if it leaks switch back to conventional oil.

 

YES !!!

I've posted this before - I saw a letter written to an engine builder from a shell oil tech - the engine builder had asked if the Diesel Rotella (the old blend WITH a good zink package) was applicable for our engines.

The tech's response was a resounding NO - stating that the oil was never intended to operate in an engine spinning faster than a diesel would ... there were very little or no anti-foaming agents and that spinning an engine at 5-6K or higher would beat it into a froth taking several hours for the aeration to subside.

... I gave my remaining 5x 1 gal. jugs to a friend with a diesel truck

 

So my rear main is leaking a little, it might increase, I'll keep an eye on it.:TU:

WOW thats good to know I browse this site a lot and missed that information, my motor spins 3800 tops, but that's going to change this winter when I file down th govener:Brow:
thanks Bruce

 

i would use the multigrade oil especially in the winter (in ontario). SAE 30, single grade, in winter startup could cause damage. it is quite thick when cold.
i have never uses a single grade oil in any vehicle that i have owned.