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Discussion Starter #1 (Edited)
LS 5.3 .018-.002 rods .003 mains. New block with Durobond cam bearings, new cam, vacuum pump, remote filter wix #51060 or 51060R. 3qts of 10/30 and 4qt 20/50. This is a new engine I have only ran this year (cold weather). Oil temp has only been about 100°.
On two step at 4200 has low 70s, peaks at 75 .2-.3 seconds into the run, at shift 7500 rpm mid 60s, end of run low 60s, lift and it jumps back to mid 70s for a bit.
This is a turbo charged combo, I just though this section has some knowledgeable guys that would have some input. Thanks

Concerned about the low 60s at the end of the run. Either filter acts the same. Thoughts?

Pan. Moroso Street/Strip Oil Pans 20141
Windage tray. Moroso Louvered Windage Trays 22941
Pick up. Moroso Oil Pump Pickups 24050
Oil Pump. Melling Performance Oil Pumps 10296
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Am questioning why you are mixing two different oil viscocities?? Get rid of the 20W50, it is too thick for high RPM applications, especially with your rod bearing oil clearances.
Otherwise, your oil pressure is OK. Your oil pressure is decreasing at high RPM because your oil pump cannot move the thick oil efficiently at these high engine speeds especially in cold temperatures. My recommendation is to go to a lighter oil, such as 5W20 or 10W30. Also check your remote oil filter installation and make sure that there are no "tight" 90 degree fittings being used. All lines to and from the filter mount should have gradual bends only.
 

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Discussion Starter #3
I'm and old school hard head. Knowing it doesn't need 20/50 I put mainly 10/30 in it original. Not an excuse just my old school thoughts of when I ran 3/4 race cams and jumped coke bottles. lol
I changed the oil to 10/30 last night knowing what you stated was more than likely the issue. "Your oil pressure is decreasing at high RPM because your oil pump cannot move the thick oil efficiently at these high engine speeds especially in cold temperatures. " Guess I just posted here looking for backing on my thoughts.
My remote setup has -10 hoses, one about 12" one about 16" each with straight on one end and tube 90s on the other. going into straight adapters.
 

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If cold starts are < 40F, I'd go with 5W30. Throw some 5W and 10W in the fridg and see how they react at 35-40F. As mentioned, you need to feed that tight rod clearance.
 

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With the oil temp at 100*F, there is absolutely no reason to run 20w-50. It's just robbing power and straining the pump. Engineguy is spot on.

With that blend of 10w-30 and 20w-50, the kinematic viscosity at 100*F is ~115 cSt. For comparison, an SAE 30 grade at standard operating temperature (212*F) is 9.3-12.4 cSt and an SAE 50 grade at 212*F is 16.3-21.8 cSt. So your oil viscosity at 100*F is ~10x more viscous than a 30 grade at typical operating temperature.

I saw where you said you went down to straight 10w-30 which is better. A 10w-30 at 100*F is still roughly 65-85 cSt which is still 6-8x more viscous than a 30 grade at typical operating temperature.

If the oil temp stays around 100*F, you could run a 0w-10 or 0w-5 oil and still have >20 cSt viscosity. The NHRA Pro Stock guys use a 0w-3 and operate at 100-130*F.

Your oil pressure is fine. You'd be surprised how little oil pressure you actually need.

Another note is about the cold start temperature. Just putting the oil in the freezer isn't an accurate comparison. Cold starting is about pumpability. You can have two oils, one pouring out of the bottle twice as fast as the other, but they both pump at about the same rate. This is why a cold starting performance requires a multi-rotary viscometer for dynamic viscosity.

Higher rpm likes a greater minimum oil film thickness and shear resistance, not necessarily higher viscosity. A more viscous oil that shears out of grade at high rpm is of no use to you. Basically you want heavy base stocks with very little to no VII polymers.
 

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LS pumps are crank driven and turn at engine speed. They will start cavitating not much above 7K. Even the Melling performance pump. More than the pressure drop, you're probably aerating your oil. I also agree...you're running WAY too heavy an oil which isn't helping.
 

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For endurance engine set up at about .001" per inch of bearing clearance, what oil would you guys use? I ran 30 weight on the dyno (dry sump) and it stayed at 60-65 psi through the pull once it was warmed up.
 

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For endurance engine set up at about .001" per inch of bearing clearance, what oil would you guys use? I ran 30 weight on the dyno (dry sump) and it stayed at 60-65 psi through the pull once it was warmed up.
For an endurance race engine, NA, and moderate rpm...

Oil temps - SAE Grade
<230*F = 30 grade
230-280*F = 40 grade
280*F+ = 50 grade

Of course there's exceptions to that rule. NASCAR cup engines run what is essentially a light 0w-20 with 280-290*F sump temps and 350-360*F through the bearings. Those Sonny Bryant cranks are incredibly precise.

Running the engine at 100*F isn't a problem if it's built around that temperature. The oil becomes a more critical choice as oil additives (like ZDDP) need heat to activate and start working so you'd want an oil with additives that can be more reactive at lower temperatures. Base oils that promote greater additive response are also a plus.
 

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For an endurance race engine, NA, and moderate rpm...

Oil temps - SAE Grade
<230*F = 30 grade
230-280*F = 40 grade
280*F+ = 50 grade

Of course there's exceptions to that rule. NASCAR cup engines run what is essentially a light 0w-20 with 280-290*F sump temps and 350-360*F through the bearings. Those Sonny Bryant cranks are incredibly precise.

Running the engine at 100*F isn't a problem if it's built around that temperature. The oil becomes a more critical choice as oil additives (like ZDDP) need heat to activate and start working so you'd want an oil with additives that can be more reactive at lower temperatures. Base oils that promote greater additive response are also a plus.
Thanks for the reply, this engine is a 5-8500 RPM engine. I will try a 10-30 and see where my oil temps go..
I always thought oil needed the heat to activate the anti wear additives (160+) but sounds like I am wrong
 

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Thanks for the reply, this engine is a 5-8500 RPM engine. I will try a 10-30 and see where my oil temps go..
I always thought oil needed the heat to activate the anti wear additives (160+) but sounds like I am wrong

Start with a full synthetic, high ester 5w-30 or 10w-30 with a high HTHS and high flashpoint. Red Line HP 10w-30 would be a good place to start as it has an HTHS that puts many 40 grades to shame.

Additives do need heat, but there's ways to tweak the chemistry (typically with alkyl groups) to make the additive more reactive at lower temperatures. This usually comes at the expense of oil life as those types of additives tend to be very sacrificial.

The main area of focus for the oil at those low temperatures is in the cylinders anyway where there's no absence of high temperatures. Solid valvetrains also tend to not have much of an issue generating heat in the contact points. This is becoming a common issue with PS engines as they continue to push the envelope. More reactive types of extreme pressure additives, and higher concentrations, are being required to keep the pushrods from eating themselves at >1" lift and >1000 lbs spring pressure at 10,500 rpm.
 

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Put a quality diesel 15/40 in it and forget the slight loss of oil pressure. Anything over 60psi and you are good. I use and like fuchs brand, german engineered.

Of course Polyalphaolefin will probably reply with "whipped latte" comments about diesel oil. But my constant 7500 rpm shifts of a high mile sbe ls1 and it still hasn't missed a beat proves to me otherwise.

Forget the afr's for a moment (it was the beginning of my converting to speed density tune back in january) but look below at what kind of abuse ive given this thing. It's been this way since 2016 and i have clocked up 5300 miles on my speedo since. The previous owner of the engine had 130,000 miles on the stock engine. A lot of it since i bought it has been WOT runs. I've even spun it to 8k just to see if it would get there . Still hydraulic roller, stock oem lifters, lmao

Don't you just love a free speech forum? (until it changes ownership and communists fuck it, as usual)

 

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This is one of the best oil discussions I've read in a while. For what it's worth, I agree w/ Foxwell and Launch. I built my LS2 w/ .0022-.0024 rod and main for boost. I daily it and my oil temps go nuts w/ the 4.10 gears and 90+mph on the highway for 45min a shot. I ran Rotella 15-40 and switched to Mobil 15-50, mostly because of the temp issue. The Rotella would drop 15psi, from 40 at cold idle to 25psi at idle in that 45min run. The Mobil 1 never drops below 32-33psi even after roasting it in 100+ degree heat. I want to put an oil cooler on it and get it under control and go to a thinner oil. I did have a conversation w/ Melling regarding pressures as I am running their 10295 pump w/ extra pressure. The tech guy I spoke w/ was "surprised" I was getting as much pressure as I was with the clearances I was running.
 

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Why doesn't everyone run a 0w-XX oil? Don't you want low viscosity at startup? I run a 0w-40 in my turbo 4cyl and think running a 15w-40 would be stupid when 0w is available for cold starts.
Both oils are 40 weight at operating temp, right? Why have a thicker oil than necessary during the most crucial time when you want the oil to get circulated quickly?
Could you guys school me on why this isn't recommended for everyone?
 

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Discussion Starter #18
Ran 8 qts of 10/30 and it made no difference. These are two similar runs with similar temp. I'm not 100 % sure of the accuracy of the 100 degrees but I'm sure these are constant in temp. Is it typical for the pressure to raise when you lift?
RCM the pan vac is in kpa it never goes positive, it is boosted and is under 30+psi in these runs.
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Why doesn't everyone run a 0w-XX oil? Don't you want low viscosity at startup? I run a 0w-40 in my turbo 4cyl and think running a 15w-40 would be stupid when 0w is available for cold starts.
Both oils are 40 weight at operating temp, right? Why have a thicker oil than necessary during the most crucial time when you want the oil to get circulated quickly?
Could you guys school me on why this isn't recommended for everyone?
In order to formulate a 0w-xx oil, you need either high amounts of viscosity modifier. The viscosity modifiers are typically olefin copolymers and aren't very shear stable. They are susceptible to both temporary and permanent shear. Some are much better than others. It's not worth losing shear stability and thermal stability at full operating temp and conditions just to get a little lower viscosity on cold starts. Take Mobil 1 0w-40 for example which has a high temp, high shear (HTHS) rating, at 150*C (302*F), of just 3.52 cP. By comparison, Mobil 1 High Mileage 10w-30 is 3.58 cP. The polymers needed to achieve that wide 0w-40 spread causes it to not hold up well to high heat and shear.

Also note that above about 0*F, there is little to no difference in viscosity between a 0w-30, 5w-30, and 10w-30. This really only becomes an issue on really cold starts below 0*F. Depending on the viscosity modifier polymers that are used, you can actually have a 0w-30 that's more viscous at 100*F than a 10w-30.
 
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