Duramax Diesels Forum Truck of the Week
  #1  
Old 06-28-2010, 08:43 AM
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Default 20w-50 oil

Ive been running regular rotella 15w40 in my truck since new, but now im starting to notice my oil pressure is getting lower as the summer gets hotter. When I say low I dont mean low like what people normally complain about on duramax's (20-25 hot at idle)....I mean low like 16psi hot at idle if I get off the highway and come quickly down to a stop. My truck would only barely make the required 42psi by 1800rpm minimum spec as well.

I dont know why, maybe its because of the twins, maybe its because this engine was a GM test engine and god only knows what they were doing to it during testing etc....

When its really hot out, like 90*+, you can even BARELY hear, not really a knock, but just a unhappy 'really low oil pressure' sounding noise.

I wasnt due for an oil change, but the summer isnt getting any cooler so I had to at least try something. So I went to the auto parts store and got some 20w-50 and a new filter. Changed the oil and now I get 19psi HOT at idle after running it really hard and coming quickly down to a stop. If I let it sit and cool a bit Ill get a little more than 19psi. On the highway at 80mph I get almost 60psi and at 1800rpm I have a little under 50psi. Not as much as I would like, but its much better than before, and the engine doesnt make anymore expen$ive-sounding noises HOT at idle now.

All of these oil pressures are read from the tech 2/efilive.

Just my experience, thought I would share...

ben
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Old 06-28-2010, 09:01 AM
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I run that Mobile 1 oil, but I've got a fresh engine with H series bearing, hot idle around 28 ish, 60 mph cruise, 65 ish, an cold pressure is off the guage, I do like this oil the engine does seem alittle quieter, than when I run Rotella in it.
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Old 06-28-2010, 09:10 AM
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Subscribing.
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Old 06-28-2010, 09:15 AM
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wow my oil gauge is way off in my truck then.. i run at about half way between 0 and 30 in hot idle, and a about 45ish at 65...maybe this is what is causing my knock???
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Old 06-28-2010, 09:17 AM
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I am curious to know how running a higher weight, more viscous oil changes your oil pressure.
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2005 LLY
6 inch fabtech lift
PPE standard xcelerator
35 inch Toyo Open Country AT
17 inch BMF M80 Death Metal Black





I'm thinking of wiping my ass with it, then mailing it back. They should be able to determine everything they need to know by the poopstain. They see the stain, examine it closely, then check the tax records for the information they seek...[/QUOTE]


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  #6  
Old 06-28-2010, 09:21 AM
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the factory oil pressure gauge is accurate (it doesnt "lie" like some people might say the coolant temp gauge does) but its best to get an actual digital "number" reading with the tech 2 or efilive
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BT DieselWorks, LLC - EFILive tuning - Duramax/Allison/gasser STANDALONE HARNESSES - Allison lockup controllers - Allison tapshift kits - Digital DSP-5 switches - full assortment of great electronic improvements and gadgets for your GM truck/SUV

All products available for sale through our online store at www.btdieselworks.com

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Last edited by duratothemax; 06-28-2010 at 09:48 AM.
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Old 06-28-2010, 09:22 AM
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good you clarified that because I don't understand how you can make a gauge lie especially on a 45k truck.
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2005 LLY
6 inch fabtech lift
PPE standard xcelerator
35 inch Toyo Open Country AT
17 inch BMF M80 Death Metal Black





I'm thinking of wiping my ass with it, then mailing it back. They should be able to determine everything they need to know by the poopstain. They see the stain, examine it closely, then check the tax records for the information they seek...[/QUOTE]


Good stuff
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Old 06-28-2010, 09:23 AM
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i thought my PSI was normal. now this might b my knocking noise
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Old 06-28-2010, 09:47 AM
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Quote:
Originally Posted by duratothemax View Post
the factory oil pressure gauge is accurate (it doesnt "lie" like some people might say the coolant temp gauge does) but its best to get an actual digital "number" reading with the tech 2 or efilive

I concurr sir, I have the digital temp gauge I don't trust the analog. LOL
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02 Duramax, LB7 lots of toys, 150 hp Injector and match CP3 from Industrial Diesel, Ported Fuel Rail Fitting Out of an 03, FASS Fuel System, GT 3788 Turbo, Stage II Port and Polished Heads, Street Cam with Upgrades to Valves, Springs, Push Tubes ect. ARP Head and Crank Studs, Crank and Cam Keyed, 20 over Malhe Pistons, Piston Skirts Coated, and Bowl delipped, Carrillo Rods, Modified Oil Pump, Banks Intercooler, Suncoast with all the triming, Suncoast Transfer Case Bracket, BD Manifold with MBRP 4 to 5 inch Stackes with resonator, Stage III Snow Water/Meth, Bullydog Propane, Twin Electric Fans, EFI LIVE, Maxx Torsion Keys, Firestone Air Ride, Cpeks with BF Goodrich.

My friends call me Dino like in the Flinstones

Be Safe An Enjoy The Ride

A Picture is worth a 1000 words, or in this case 1000's of dollars.
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Old 06-28-2010, 09:48 AM
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Quote:
Originally Posted by kman2468 View Post
i thought my PSI was normal. now this might b my knocking noise

When do u notice the knock???
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02 Duramax, LB7 lots of toys, 150 hp Injector and match CP3 from Industrial Diesel, Ported Fuel Rail Fitting Out of an 03, FASS Fuel System, GT 3788 Turbo, Stage II Port and Polished Heads, Street Cam with Upgrades to Valves, Springs, Push Tubes ect. ARP Head and Crank Studs, Crank and Cam Keyed, 20 over Malhe Pistons, Piston Skirts Coated, and Bowl delipped, Carrillo Rods, Modified Oil Pump, Banks Intercooler, Suncoast with all the triming, Suncoast Transfer Case Bracket, BD Manifold with MBRP 4 to 5 inch Stackes with resonator, Stage III Snow Water/Meth, Bullydog Propane, Twin Electric Fans, EFI LIVE, Maxx Torsion Keys, Firestone Air Ride, Cpeks with BF Goodrich.

My friends call me Dino like in the Flinstones

Be Safe An Enjoy The Ride

A Picture is worth a 1000 words, or in this case 1000's of dollars.
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Old 06-28-2010, 09:50 AM
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FWIW the factory low oil pressure warning (chimes and "OIL PRESSURE LOW" displays in the driver info center) comes on at 7psi. I raised the warning threshold in mine to 15psi just because.... You can do this with efilive.
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BT DieselWorks, LLC - EFILive tuning - Duramax/Allison/gasser STANDALONE HARNESSES - Allison lockup controllers - Allison tapshift kits - Digital DSP-5 switches - full assortment of great electronic improvements and gadgets for your GM truck/SUV

All products available for sale through our online store at www.btdieselworks.com

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Old 06-28-2010, 09:55 AM
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Quote:
Originally Posted by wdino73 View Post
When do u notice the knock???
while under throttle, not sure about full throttle because then i cant hear it bcause of my exhaust
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Last edited by kman2468; 06-28-2010 at 10:04 AM.
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Old 06-28-2010, 10:02 AM
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Quote:
Originally Posted by duratothemax View Post
FWIW the factory low oil pressure warning (chimes and "OIL PRESSURE LOW" displays in the driver info center) comes on at 7psi. I raised the warning threshold in mine to 15psi just because.... You can do this with efilive.
Thanks I didn't know that, that would give u a safety net, if I'm understanding that correctly??
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02 Duramax, LB7 lots of toys, 150 hp Injector and match CP3 from Industrial Diesel, Ported Fuel Rail Fitting Out of an 03, FASS Fuel System, GT 3788 Turbo, Stage II Port and Polished Heads, Street Cam with Upgrades to Valves, Springs, Push Tubes ect. ARP Head and Crank Studs, Crank and Cam Keyed, 20 over Malhe Pistons, Piston Skirts Coated, and Bowl delipped, Carrillo Rods, Modified Oil Pump, Banks Intercooler, Suncoast with all the triming, Suncoast Transfer Case Bracket, BD Manifold with MBRP 4 to 5 inch Stackes with resonator, Stage III Snow Water/Meth, Bullydog Propane, Twin Electric Fans, EFI LIVE, Maxx Torsion Keys, Firestone Air Ride, Cpeks with BF Goodrich.

My friends call me Dino like in the Flinstones

Be Safe An Enjoy The Ride

A Picture is worth a 1000 words, or in this case 1000's of dollars.
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  #14  
Old 06-28-2010, 10:04 AM
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I don't remember what diff it made when I was running Cenpeco 20w-50 vs 15w-40 in my LLY (any little bit helps in an LLY) but it did add a few psi when warm. I might actually go back to it this next change and can chime in again then. I ran Mobile 1 once and never again. I believe in it in my gassers but it was too thin. Only time my Dmax ever used a noticeable amount of oil between changes.

Anyone ever conclude why the LLY is so much lower than the LB7?? My LB7 with 157k on it would damn near peg it at start up and then hover at 40psi most of the time.
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Old 06-28-2010, 10:18 AM
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definitely noticed an improvement in acelleration and turbo spool too.
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2012 Denali - R&D testbed for upcoming new products.....
2005 Silverado LT - Blown up/broken too many engines and parts to care about making it fast anymore, so its back to mostly stock - The best names in the industry for parts/advice/help...MikeL.Guy-SoCal.Rob-ATP.Evan-Limitless.McRat.BigDipper.Bobo.Tony-RRDP.Fingers.Eric-MA.EFILive...


BT DieselWorks, LLC - EFILive tuning - Duramax/Allison/gasser STANDALONE HARNESSES - Allison lockup controllers - Allison tapshift kits - Digital DSP-5 switches - full assortment of great electronic improvements and gadgets for your GM truck/SUV

All products available for sale through our online store at www.btdieselworks.com

Be sure to "like" us on Facebook at www.facebook.com/BTDWorks
Be sure to "follow" us on Instagram @btdieselworks
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