oil Recommendation for a vortec extending OCI'S

[vorteXtreme759]

Hello all I purchased a 1999 gmc safari van with 140,000 about a year ago, as soon as I got the van home I changed the oil with mobil1 high mileage 10w30. before I did the oil change the van had around 60Psi cold idle, 40 psi warm.

But about a week after the oil change the oil pressure started dropping I didn't pay much attention to it as people told me the chevy oil pressure sending units were unreliable.. But another week passed and the motor started feeling strange like I was pulling a trailer. At this point my oil pressure gauge was reading 30psi cold, 10psi or less at warm idle. Well finally @ 1200 miles on the mobil1 high mileage synthetic the motor spun a rod bearing!

So I decided to replace the engine myself! As I just bought the van and wasn't about to lose $3500 I payed for it. But This just seemed so strange for a healthy engine to just eat itself AFter a premium oil change! So I dropped the oil pan expecting to see the oil pump screen plugged with deposits that the synthetic oil had broken down. But it was the opposite the oil had a Silver color and lots of metal on the magnetic drain plug. But the motors internals were a pretty gold color! Hmm mm confused and determined I tested the oil pump and It worked just fine! Soo yeah idk.

But at this point I still needed a motor so I got one from my local pick and pull, I got the motor from a 2000 chevy astro with the newer roller cam & roller rockers. While I was in the motor I changed all the seals and installed a melling hi volume oil pump, I also removed the oil cooler as there prone to leak. I then got it installed in the van. I now have 75-80psi cold idle and 40-50psi warm idle with 5w30 mobil extended performance.the oil pressure seems like more than enough, so I was wondering if I could get away with running thinner oil maybe 0w30 or 5w20? And thinking of switching to amsoil so I can extend my oil change intervals? I searched but I couldn't turn up any results for extended oil changes with the 4.3 vortec, just how long can i extend the interval and what brand?
& Thank you for taking the time to read this

 

[Garak]

There would be nothing wrong with something like M1 AFE and a 10,000 mile OCI. I had to say it, since I haven't seen tig1 on for a few days.

 

[simple_gifts]

You forgot to mention "no issues"

 

[Dufus2]

I just had a 97 5.7L re-manufactured and the shop is picky about Rotella 15w40 as their only choice of motor oil... The pressure control valve in your old engine must have stuck dumping the oil pressure, its a common problem with a grit of dirt or metal and thats why it was destroyed.

Personally, I like the 30W diesel oil Amsoil sells because it is like a conventional 10w30 with better protection. My OCI in a 2-1/2 qt Toyota was 10K miles and it ran flawlessly until vandals messed up the engine.

This is a good oil and don't fall into all the hype of the Signature series 0w30 as an alternative to a more viscous oil because even the fine print states not for heavy use (towing etc).

Rotella, Delvac and other 15w40 diesel oils are an excellent choice for cleanliness and its available everywhere at a good price. Even neglected work trucks do well running diesel oil without having engine trouble.

Just do your research from what the people here suggest and it will be just fine.

 

[simple_gifts]

Quote:

don't fall into all the hype of the Signature series 0w30 as an alternative to a more viscous oil because even the fine print states not for heavy use (towing etc).


The fine print I see says frequent towing is considered severe service. Can you post the link where it says "not for towing?"

 

[901Memphis]

With a high volume pump and that kind of pressure you could probably get away with something thinner. If you want to take baby steps try M1 HM 5w20 which is toward the higher end of 20 weight hot.

Alternatively you could just go straight to a 5w20 synthetic like AFE and monitor pressure with it. I'm not sure how reliable your gauge is though. A mechanical gauge would be ideal.

 

[JR]

A vortec will run on a "20" weight just the same as a "30".
I have a 98 astro awd with 215k. running on 5w20 for over 125k.

Ken

 

[vorteXtreme759]

okay well sounds like I would be perfectly safe to run 5w20 in this motor. so mobil 5W20 would probably be the best shot. I guess I'll try the 5W20 for a couple of changes and maybe have a oil analysis performed at the second oil change.
although for some reason I'm still scared of putting a 5W20 in this motor. I'm glad to hear the recommendations and that people have used 5W20 in these motors I just need some reassurance.

 

[901Memphis]

The oil pressure is a major part of your assurance I would think. If it's below spec you know you gotta go back to oem.

 

[vorteXtreme759]

well i guess I forgot to mention how I use this vehicle I'm currently using the vehicle to pull a trailer around 2,000 pounds with mixed city/Highway driving in Florida. with that being said am i asking too much by switching to a 5W20 and wanting to lengthen my oil change intervals?

 

[Kuato]

Won't go wrong with Amsoil.

 

[clinebarger]

The engine most likely had Coolant in the Crankcase at one time, Antifreeze is very hard on Tri-metal inserts.
Fuel dilution is another possibility.

That HP/HV oil pump is a mistake, Your making Too Much pressure...80 psi cold & 50 psi hot idle is ridiculous. Your going to go through distributor gears, The original one you have will strip in the next 20K miles if your lucky, Then a new one will last around 50K.

A stock oil pump is good for any stock engine, And for most performance builds given clearance's are not too loose.

 

[wtd]

The factory spec oil for that engine is 5W-30 and is what I would use.

Wayne

 

[vorteXtreme759]

[censored], you confirmed exactly what I was thinking. I've already went through one distributor gear.. And I too worry about the extra load on the dizzy gear. .

I called the oil pump manufacturer and they told me this is a high volume pump (25%more volume) not high pressure. They say the pressure is normal for a healthy 4.3 And assured me I won't have a problem,

but your correct the high volume pump will put more stress regardless of pressure because the unnecessary extra volume will just hang the oil pump pressure bypass open and add more stress to my oil, dizzy gear, and a small power loss...essentially turning it in to an oil blender/aerator pooooo!

I guess I will be changing the oil pump out soon for a standard volume.

 

[pair of Blazers]

I have been running AMS oil ACD 10/30 in my 01 Blazer w/4.3L for yrs doing 10K oci in northeast. search my UAO's for the Blazer. you won't be disappointed.

 

[Garak]

Originally Posted By: vorteXtreme759
I called the oil pump manufacturer and they told me this is a high volume pump (25%more volume) not high pressure.

Considering flow is volume per time unit and pressure is resistance to flow, I'm not sure how they can make that statement when nothing was done to the engine to remove any impediments to flow in the first place.

 

[vorteXtreme759]

I agree this pump is not necessary in my application, I originally installed it thinking it would help pick up the volume lost thru the oil cooler. but I have since removed the oil cooler.

 

[vorteXtreme759]

Should I put the oil cooler back on? Or just cut the [censored] cake and put a standard pump back in?

 

[The_Eric]

I personally believe you'll be fine with the HP/HV pump. I've seen too many installed live out long, happy lives. Many rebuilders even ship them on their re-mans. While not what you need, it'll serve you well enough. If you do happen to have a distributor gear issue, do yourself a favor and go to the GM dealer for the replacement. The aftermarket parts are nearly always low grade Chinese stuff. The OE part, even if an import is of greater quality. This a lesson I've learned the hard way.

The cooler would be a good thing, but not absolutely necessary.

Bottom line- run a light 30 grade oil like Mobil 1 AFE or Penz Platinum 5w-30 to minimize cold start load on the pump and extend your service intervals to maximize the ROI (or at least somewhat justify the cost).

 

[vorteXtreme759]

Correct me if I'm wrong but isn't the 4.3 oil pump the same pump that came on the 5.7? If so that would make the standard v6/v8 pump more than enough for a v6 seeing as the v6 has one less main, Two less rod's, & two less lifters to feed. Making the v6/v8 hv pump extremely overkill. Or am I over thinking this now?