MotorHead17

You got a lower reading with the mechanical gauge? Nice looking set up by the way.

Double J

iTrader: (3)

Thank you. Yes lower readings when oil is hot. Running 10W30 HPS Royal purple. 30- 40 psi at idle. When I rev motor it 60-80 psi. Guess that's ok right?

MotorHead17

Ya, that's great oil pressure. My ls1 trans am idles at around 20. Doesn't go much past 50 though.. It's a 98 and those are known to have oil pumps go out.. I think I might be replacing it soon here before it goes bad.

ahritchie

iTrader: (1)

Speak of the oil pressure demons in the LT1 and they shall appear! I was driving in heavy stop and go traffic on a 80+ degree day the other day, the water temp creeped up to 210, and the "check gauges" light flashed once when I came to a stop, looked at the gauge and oil pressure read just above the red zone... 5-10psi This is a fresh LT1 (383 however) with only 5K miles on it. The oil pressure jumps right up as soon as I touch the gas and it normally idles with much more oil pressure when the water temp is 180-190. I'm using 5w30 Mobil 1 FWIW.

Meanwhile, my LS1 with 167K has a hot idle of 30-35psi all the time.

MotorHead17

I talked to a guy who works at GM the other day (actually knows his stuff unlike a lot of other techs I know) he said the gauge clusters will usually read low and he always said it's the nature of the beast with them having low oil psi at hot idle. He said "they just don't need that much oil pressure at idle to survive" He also told me that he's always ran 15w40 in all of his SBC engines. So, that's what I'm going to do.
Since were talking about crappy things that have happened though, my t56 locked up on the first drive after I overhauled the whole car(engine work, suspension work, different rear end, new paint)

Shownomercy

iTrader: (1)

I would recommend swapping out the plastic coupler oil pump driveshaft for a ARP or similar if you are gonna run that heavy of a oil.

MotorHead17

I didn't think of putting an ARP one on when I was in there. I did put a new Felpro one on though. I don't think I'm going to run 15w40 the more I think about it. I'm just going to run 5w40 T6 synthetic.

myltwon

iTrader: (1)

They're different engines with different oil pressure requirements, if a LS1 got anywhere near the lower end of the acceptable oil pressure tolerances of an LT1 you'd be looking at a rebuild.

ahritchie

iTrader: (1)

Yeah, that's kinda the point I was getting at; it's an apples to oranges comparison....it's definitely a LT1/gen 1 specific issue that should not be too much cause for worry. Tighter engine tolerances in "modern" engines I suppose makes the difference.

savage388

Could the whole lt1 low oil pressure issue come from the reverse cooling design not sufficiently cooling the bottom end of the block? If so shouldn't an oil cooler solve most of the oil pressure problems the lt1 has. I have to wonder, if reverse cooling was so great why not give the ls1 the same design.

MotorHead17

m
The earlier LT1's came with oil coolers (think the factory started removing them in 96) that did not really do much. Most people remove them just to gain a few psi of oil pressure.

Shownomercy

iTrader: (1)

Pretty sure GM got their asses sued for stealing the reverse flow design,which is why it died with the crappy LT1. I think.

People run filled blocks with no issue of oil pressures in race car world, not sure why the LT1 stock would suffer that much heat soak. If you are interested, toss in a temp sensor and start datalogging.

My guess, these things are over two decades old and slipping fast into the cheap enough for any high school kid to own and then not afford the proper maintainance. They are robust but won't survive forever.

MotorHead17

I can afford the maintenance Just redid most of the car... haha

savage388

the coolant temp sensor in the PCM will read 230-240 regularly, even though my dash gauge hovers around 190 and the fans aren't running, so the coolant temp does get pretty high down in the block. vetted came with an oil temp sensor, I'd be interested to see what kind of temps they see compared to a say an l98.

ahritchie

iTrader: (1)

The idiot light comes on in a 1996 LT4 Corvette is at 300 degree oil temp! And they do run that hot when pushed enough on a track.

savage388

that's really hot, I can't imagine that's doing the oil or bearings any favors in the long run. Normal sbc's run what about 40-50 degrees cooler, 300 degree oil temps and most people would immediately shut it down.

ahritchie

iTrader: (1)

LT4 came with Mobil 1 synthetic stock; that's why! Synthetic oil doesn't thin out with high heat from sustained high rpm like dino oil Road course designed engines have to deal with a lot tougher conditions for more than 12 seconds or so at a time and last doing it; The new 2015 supercharged LT4 runs that hot too on a track! (again with the synthetic oil) GM sells them with a warranty for track use and specifically only recommends Mobil 1 (or risk severe engine damage supposedly ) I guess that's a pretty good endorsement for synthetic for me!

Shownomercy

iTrader: (1)

Synthetic oil? Sure, but claiming M1 is awesome cause its OE GM is lulztastic IMO.

UOA from countless dmax guys is always great running dyno T3 oil, and thats with a 1400* turbo cooking oil.

All depends on your speficic combo.

ahritchie

iTrader: (1)

I don't care about the brand personally; GM however does though....I've run Castrol Syntec, Mobil 1, Royal Purple and just prefer the added protection of synthetic for how I beat on my cars, and longer oil change intervals.

Duramax diesel is an apples to oranges comparison; those have an oil cooler (that actually does something) from the factory, take 9 quarts of oil, also the max oil temp spec is only 275, is a diesel truck engine, not a high performance gas engine that spins 7K RPM for extended periods on a racetrack generating well over 1 G cornering forces. They were designed with plenty of capacity to cool the oil for a turbo. RPM raises oil temp more than just turbo generated heat would anyway.

myltwon

iTrader: (1)

GM recommends Mobil 1 because mobil payed them a bunch of a money to stick their logo on the fill cap

Diesels may not rev like a conventional motor but most are designed to run on hot forced air (turbo) and haul large payloads. It is apples to oranges but neither a "race" motor or a rightfully purposed diesel truck is a low abuse motor. Heavy hauling can be just as intensive as high rpm.