Choosing an oil pump (V8 / LS engines)


Lifetime VIP Supporter that Sierra #2 is driveable again, I noted that its oil pressure reads a bit lower than Sierra #1's does.
Still within 'spec', and I need to read both with Torque, or hook up a mechanical gauge, to see if there really is a delta between the two.

Background info (both are 2003 LQ4 engines)

Sierra #1:
  • About 250K miles.
  • Other than an intermittent misfire on #5, this motor is a strong runner.
  • Oil pressure runs from about 30-42 psi, from idle to about 2500 rpm. (per gage)

Sierra #2:
  • About 230K
  • Has a bit of a rough idle, and I need to correct this. Has good power, otherwise - similar to the other one.
  • Oil pressure runs ~ 24- 38 psi, idle - 2500 rpm (per gage).
:undecided: -- I know the numbers sound similar, but looking at the sweep, the pressure just seems so much 'lower' (since the other one crosses the halfway point on the gage, you get the idea...meanwhile, this one doesn't get 'to' the halfway point).​
Yes, I'm aware that this is really nothing to worry about... GM spec is minimum 10psi for every 1000rpm.​

Now, my plan has been to put in a tow cam - originally with the Envoy, then with Sierra #1, and I've finally settled on Sierra #2 to get the 'goodies'. Along with the cam would come all the other things -- e.g.; springs, lifters, pushrods, everything up front that comes off to get to the cam, including the timing chain & an oil pump.

As far as what oil I plan to run...synthetic 5w-30. Most likely M1 'high mile / ext. performance' version. Planned mileage would have me at 1-2 changes a year, max (not including top-ups).

Given the (supposedly) lower psi on this motor, and considering 4500rpm would be about the highest this motor would see (most of the time, it would be at 3000 or below, even in tow/haul mode)...

I could either put in a 'stock' type pump (Melling M295), or a 'high volume' Melling 10295.

Another option would be a 'high pressure' 10296, and you might think I'd head straight for that option, since I'm talking 'pressure'...but it seems from my research that high-pressure pumps are more for high RPM / racing type motors (?) That's not my plan, here...I want the low- / mid-end grunt, not the top-end HP.

I'm leaning toward the 'HV' 10295, but if the M295 would be sufficient, I won't argue about it. Melling's a trusted name in this area.

IIRC, GM Performance also has a better pump option over stock (and cheap, too!), but I think I'd go with Melling.

I'm aware that a new O-ring joining pump <> pickup tube would be in order (already have it, actually), and since this particular truck is a 2WD, I'll probably pull the pan & put a new gasket in (have that, too), so I won't have trouble getting to the pickup tube, plus I can take off the windage tray and take a look at the bottom end while I'm there. I'm also OK (after seeing this on YT) with shimming the inner / outer gear on the pump (done to ensure they're centered within the pump housing, relative to the crank snout)

Since I promised myself not to get 'full-bore' into this before getting the other truck sold, I'm not in a rush here. But it's definitely time to start planning 'what' to get, and I'm interested in hearing from those who've done this with a motor (whether for tow, race, or some other purpose)

If anyone wants the info on the other parts on my build list, let me know, but for now, I'll keep this thread to just the oil pump, and what would be 'best' for my application.


Direct from the man, you should use a high volume high pressure 10296 pump:

So that means you'll be dropping the pan? Or using D-Ray's trick?

I did that during my cam swap except that the bracket was welded to the tube so I used washers instead. I have found a part that can also be used:


Lifetime VIP Supporter
Appreciate the quick reply (and I saw your post from 2017 re: D-Man, when I was searching the forum...which is another thread... "how to search, and actually get the result set you hoped for" -- hint: use double-quotes)

Anyway...while I was looking at the part you linked to, and after bouncing over to look at the 10296, I came across this: ($19.95 USD vs $34.00 -- and it's made from billet aluminum, too)

Thx for linking D-Man's video - informative, to say the least. And I will drop the pan, when the time comes, just because I don't have to worry about removing a front diff / IFS, being a 2WD. Plus, with 230K, I'm interested in seeing what's in the bottom of the pan, and will give it a good cleaning, as well.

Given my experience with the bearing caps from the rear diff, maybe I'll stop at the pan, vs. also removing the windage tray...but the pan is pretty much a given. Plus, I think it has a slight leak, so I may as well repair it, since I have the new gasket. for George Melling's advice...the nice thing about the 10296 is that it comes with the weaker spring, in case you don't want to run 'high volume and high pressure'. So if I get that pump, there's a good chance I'd swap that weaker spring in. Will be doing some off-site research on that in the coming weeks. I've seen some info that suggests Hi Pressure might not be what is best, for my application. We'll see. And perhaps someone else will weigh in to confirm / refute that.

Also noticed that Melling makes a M295HV - a HV version of the stock-style. That's a possibility, too.


Good find on that girdle. Crazy thing is that it sells here for $80 on and that first one id $45. If you're really paranoid, you could use one of these too since you're pulling the pan:

At least you're doing due diligence on this. I didn't and I have low oil pressure in my Saab. I put a regular 295 in my DOD deleted 5.3 and it has lower than normal pressure. So much so that it trips a code when the oil starts getting older (~50% OLM). To get rid of it, I have to change the oil. I would have to replace the pump with the one for a DOD engine but the Saab's future is uncertain at the moment.

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