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I talked to Melling about the right oil pump and they suggested the 10295 unit if my hot idle oil pressure is 25 PSI or above and the 10296 unit if it is below that. After finally replacing the oil pressure sending unit as part of a refresh, I find that the hot idle oil pressure sits steady at 20 PSI. The car is due for an oil change. Oil is always Amsoil 5w30 Signature series.
I am under the assumption that Melling knows what it is doing, but wanted some extra opinions to build my confidence that the 10296 is the appropriate pump.
I agree with SoCalDave, M295 will most likely work for you. I have used 2 of the rebranded Summit M295 pumps on 2 different LS based engines both had high mileage. I installed a shim/washer to the relief spring to up the pressure about 10psi. Worked great... less money
I’ve seen many, many oil pressure senders change what the gauge says. You very likely have more than 20 psi at idle being that your engine has been maintained well. I wouldn’t sweat it at all. Leave it alone. Regarding the two pump choices, more volume will be required to up the idle pressure, so the 10296 would fit the bill for more pressure at idle. But with the 2000 LS1, all you should need would be the 10295. Shimming the relief spring in the pump will do nothing for idle pressure…that’s only going to help max pressure situations.
Again, I’d bet your new OPS changed the gauge reading, and your actual pressure at idle is higher.
I’ve seen many, many oil pressure senders change what the gauge says. You very likely have more than 20 psi at idle being that your engine has been maintained well. I wouldn’t sweat it at all. Leave it alone. Regarding the two pump choices, more volume will be required to up the idle pressure, so the 10296 would fit the bill for more pressure at idle. But with the 2000 LS1, all you should need would be the 10295. Shimming the relief spring in the pump will do nothing for idle pressure…that’s only going to help max pressure situations.
Again, I’d bet your new OPS changed the gauge reading, and your actual pressure at idle is higher.
How do I know what my oil pressure is?? The OPS was a GM-branged AC Delco unit, is it not trustworthy? I may need to reset the computer.
How do I know what my oil pressure is?? The OPS was a GM-branged AC Delco unit, is it not trustworthy? I may need to reset the computer.
How does the pressure look at cruise rpm? You will have to connect a manual gauge and compare the two simultaneously if your concerned about it. I wouldn’t think twice about 20 psi at hot idle unless I had a reason to warrant it, such as metal in the filter or an unusual noise has crept in. Cut the oil filter open…the filter never lies.
Brand of OPS really doesn’t matter for quality these days unfortunately. Most guys over on Corvette Forum seek out the brass bodied OPS units when these fail, and for some reason, they fail on the C5’s often. I have a 27k mile C5Z that’s already had to have one changed out. I’ve seen anywhere from 5-7 psi difference between OPS’s, out of the box. The gauge is simply there for you to monitor, not be accurate by any means. Keep an eye on it, and if it drops from the 20 psi hot idle in the next little while, then you may have an actual bearing issue going on, but again, the filter will show you that.
How does the pressure look at cruise rpm? You will have to connect a manual gauge and compare the two simultaneously if your concerned about it. I wouldn’t think twice about 20 psi at hot idle unless I had a reason to warrant it, such as metal in the filter or an unusual noise has crept in. Cut the oil filter open…the filter never lies.
Brand of OPS really doesn’t matter for quality these days unfortunately. Most guys over on Corvette Forum seek out the brass bodied OPS units when these fail, and for some reason, they fail on the C5’s often. I have a 27k mile C5Z that’s already had to have one changed out. I’ve seen anywhere from 5-7 psi difference between OPS’s, out of the box. The gauge is simply there for you to monitor, not be accurate by any means. Keep an eye on it, and if it drops from the 20 psi hot idle in the next little while, then you may have an actual bearing issue going on, but again, the filter will show you that.
Cruising on the highway at ~1500 it sits around 28 psi, after having driven the car for awhile the hot idle pressure was at 18 psi. I'll report back later after I have reset the computer, doubt that will make a difference but I can at least check that off as a possible discrepancy.
You probably need to change the rear cover gasket and the cam plate. My 01 Camaro was getting close to 20 psi hot idle so I swapped to a Melling M295 oil pump which improved things a bit. Not long ago I changed the rear cover gasket, rear main seal and oil pan gasket. Oil pressure is solid now.
You probably need to change the rear cover gasket and the cam plate. My 01 Camaro was getting close to 20 psi hot idle so I swapped to a Melling M295 oil pump which improved things a bit. Not long ago I changed the rear cover gasket, rear main seal and oil pan gasket. Oil pressure is solid now.
Good to know. I have done all of the topside gaskets(plus the recommended sealing of the knock sensor covers) and next I am replacing the harmonic balancer with a unit from ATI as well as swapping the timing set with a TX3 unit from Cloyes, so all of the gaskets and seals will get replaced in the process. After that the clutch will be next on my list of things to attack and will completely refresh the drive train save doing a rebuilt on the differential. Basically every gasket was leaking except for the intake manifold, which I had replaced while installing a new OPS... which obviously failed.
I’ve seen many, many oil pressure senders change what the gauge says. You very likely have more than 20 psi at idle being that your engine has been maintained well. I wouldn’t sweat it at all. Leave it alone. Regarding the two pump choices, more volume will be required to up the idle pressure, so the 10296 would fit the bill for more pressure at idle. But with the 2000 LS1, all you should need would be the 10295. Shimming the relief spring in the pump will do nothing for idle pressure…that’s only going to help max pressure situations.
Again, I’d bet your new OPS changed the gauge reading, and your actual pressure at idle is higher.
This!!! Good advice. You could shim the relief valve 1/2" (if it was possible), and idle pressure wouldnt change. OP, I have a 10296 Melling in my built, wet sump LS7 in my C5. Reason being my block was drilled for piston squirters. At 200° oil temps, 190° coolant temps, I'm seeing 25lbs oil pressure at a 900rpm idle. The mechanical gauge I once had on it, albeit BEFORE the oil filter, showed 35lbs in same situation. I run a Wix filter, and I really doubt the filter is cutting 10psi from the after filter reading. I don't think you have any problem at all. My .02.....
This is an excerpt from Corvette Central. 1997-2013 LS engines idle with 20-30PSI of oil pressure typically. On a hot day after the engine and drivetrain has warmed up, it is possible to see 15PSI at idle without any concern. The main thing to watch for is a rise in pressure once in gear. At 2000 RPM, you should see 45PSI. As RPM increases, so should the oil pressure. Most LS engines top out at 60-75PSI. When you see 0-5PSI at idle and 25-30PSI at cruising speed, you need internal engine work, not 20W50 oil. Complete article here
I installed a Melling M295 on my '01 Camaro and recently on my brother's '05 Vette; he cruises his C6 and I run my 4th Gen hard. You can go with one of the other models, but the stock replacement oil pump will do the job.
You can also mod the stock oil pump for more volume; here are a couple pics. I have a bench to work on parts, but sometimes my lifting bench becomes my second parts modification bench lol.
I did not know that, I will add that to the parts list! Thank you!
Ron's advice is very sound. The plate has what's basically an orange (unless color has changed) O-ring bonded to the backside of the plate. Over time, it flattens out from heat cycles and constant pressure from the hold down bolts. Think the carpeting in your living room. Wherever something heavy has been sitting for a couple years, there will be indentations in the carpet wherever that heavy piece was resting, like a table leg. The plate is in a critical location, because any oil leaking/bleeding off there will lower the oil pressure throughout the entire engine. A good rule of thumb is to NEVER reuse an O-ring anywhere inside an engine. This goes triple for that blasted oil pump pickup tube!!!!
Last edited by grinder11; Aug 3, 2022 at 01:11 PM.
I’ve seen many, many oil pressure senders change what the gauge says. You very likely have more than 20 psi at idle being that your engine has been maintained well. I wouldn’t sweat it at all. Leave it alone. Regarding the two pump choices, more volume will be required to up the idle pressure, so the 10296 would fit the bill for more pressure at idle. But with the 2000 LS1, all you should need would be the 10295. Shimming the relief spring in the pump will do nothing for idle pressure…that’s only going to help max pressure situations.
Again, I’d bet your new OPS changed the gauge reading, and your actual pressure at idle is higher.
I bought a manual gauge and hooked it up with some adapters(ffs trying to ensure pressure was being held was a pain). Turns out the AC Delco sensor is spot-on, at least at idle, I did not test much beyond that. Hot idle pressure is 19-20 PSI and rises significantly as the RPMs increase. @1500 rpm, or cruising rpm, the pressure sat at ~29 PSI and @5500 the pressure was around 55 PSI. So I'll assume that I do not have a bearing issue and an M295 is fine and an upgrade would be the 10295. I'll report back later on whether or not this sensor is accurate at higher rpms after taking some more data.
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Help with choosing an oil pump 
