Is 20w50 the wrong oil for my 96 9c1 (83,000 miles)?

[RDW]

Do to low oil pressure a mechanic replaced my 5w30 oil with 20w50. Guage wise; doesn't seem to make any difference. Now I have been told by other sources the 20w50 is bad for "this" car, and I should go back to 5w30. I live in the SF Bay Area, so the weather is mild. Any input would be greatly appreciated. [ March 08, 2004, 02:46 PM: Message edited by: RDW ]

 

[TallPaul]

Not sure what that car is, but I would probably have tried 10w40 first. Does your car have a real oil pressure gauge or a dummy gauge (glorified idiot light)? If a real gauge is the sender maybe bad. What pressure reading are you getting cold, hot at highway speed, hot at idle? Did the mechanic test it with a gauge? If you decide to go to 10w40 you can drain half the oil and top back up with 5w30 for approx 10w40 (not recommended long term practice, but saves tossing good oil).

 

[RDW]

TallPaul Thanks for your response. The car is a 96 Chevrolet Caprice with the Police Package ie: 9c1. It has a Real oil pressure gauge, and a new sender. The gauge reads: about 1/3 when cold, about 1/4 @ hiway speed, and in the red with the check gauge light sometimes coming on at idle on a warm engine.

 

[Propflux01]

I would go with a 10w-30 instead of the 5w-30, what guage readings were you getting, I.E. did you hook up a direct pressure guage and see what it is actually reading? I would not put too much trust into a dash guage, alot of them are preset to go only to a certain point on the dial once oil pressure is achieved, no matter what the pressure is. Just the same as the above poster was talking about. Unless you have major mechanical issues with teh car, I would not use the 20w-50.

 

[tpi]

How clean is the engine internally? The heavier grade should increase oil pressure if the bearings are worn. Possibly you have a plugged intake screen and that accounts for the lack of change with heavier oil. You may want to have this checked. I have owned SB Chevys which had low oil pressure on hot engine, and have received good service from them anyway. But these engines lost oil pressure due to too large bearing clearances or oil pump clearances.

 

[RDW]

"How clean is the engine internally?" Don't know I am 1,100 miles into the ARX clean process.

 

[DavoNF]

It would be best to give the engine a good flush or AutoRx treatment first. You should see a noticeable improvement in pressure going from a 5-30 to a 20w-50. After the clean out, I would go a 15W-40 in winter and the 20W-50 in summer. I live in a climate similar to yours, and would never use a 5W-anything. I might even suggest that this light oil caused premature bearing wear (me puts on fireproof suit}. I mean 83,000 isn't a very high mileage for your engine. Dave

 

[TomJones76]

I have a 96 with the same LT1 engine you have. On the GM "idiot" oil gauge the factory gave me, I get a 2/3rds reading pretty much the whole time the thing is running. Don't know if that's a useful data point or not. By the way, this LT1 engine will give you fine results with a heavy 30 WT or normal 40 WT oil. A 20W50 will probably not be too far out of grade versus what is ideal in this engine.

 

[heyjay]

Are you sure you have a retired police car? The last model Chevy Caprice police package came with 4L60E transmissions and LT1 motors. The instrument cluster had a vacuum flourescent digital speedometer, with analog tach, fuel, temp, and oil pressure. In 2000, a friend of mine in Utah picked up a Utah Highway Patrol Chevy Caprice with the Police Package at a State auction: - LT1 V8 - 4L60E motor - 4 wheel disk brakes / ABS - HD suspension - 184,000 miles The UHP ran the recommended Mobil 1, but they used Mobil 1 10W-30 instead of 5W-30. He picked up the car cheap and did the AutoRX treatment immediately. The oil came out quite a bit darker after that, so he ran a few flushes with Dino and much shorter OCI. Motor is fine now, though he runs Mobil 1 15W-50 year round. The trans was slipping already so he got a new one from Pace Performance, along with replacing the factory Limited Slip with a Powertrax No Slip. Drives like new. He also got the Lingenfelter adjustable thermostat for the electric fans, so the cooling fans kick on at 185 instead of +210. For stop-n-go driving in Salt Lake City, that really helps. With the LT1 he was able to put in a "T" fitting and run a mechanical Autometer oil pressure gauge. 25-35 psi hot idle in Drive, 65-75 psi hot at Interstate speeds. LT1 motors hold up well with basic care, especially if you run a good synthetic. If the motor is worn though, you can call Pace Performance and get a crate motor LT1 for $4,146. BTW: General Motors Performance Parts recommends at least a 10W-40 in ALL their crate motors, including LT1 and LS1 motors. Hope this helps. Jerry

 

[RDW]

"Are you sure you have a retired police car? The last model Chevy Caprice police package came with 4L60E transmissions and LT1 motors. The instrument cluster had a vacuum flourescent digital speedometer, with analog tach, fuel, temp, and oil pressure". That's what I have, but without the tac. I got the car Free straight from a local PD, and it was a Black & White. I now have over $13,000 in this "free" car?!

 

[heyjay]

quote:

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Originally posted by RDW: "Are you sure you have a retired police car? The last model Chevy Caprice police package came with 4L60E transmissions and LT1 motors. The instrument cluster had a vacuum flourescent digital speedometer, with analog tach, fuel, temp, and oil pressure". That's what I have, but without the tac. I got the car Free straight from a local PD, and it was a Black & White. I now have over $13,000 in this "free" car?!

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Huh, how can you have $13 G's in a "free" car?? According to Pace Performance, a crate motor LT1 is $4,146. A replacement 4L60E is $1,734. Call it $6,000. A word of advice: DO IT YOURSELF!! Once you get a crackpot mechanic involved, he will suck your wallet and bank account dry. There are plenty of resources out there on that year Caprice, and it's WAY easier to work on than a foreign job. Check your local library for starters, then any car clubs in your area. Jerry

 

[uconn1150]

quote:

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Originally posted by DavoNF: It would be best to give the engine a good flush or AutoRx treatment first. You should see a noticeable improvement in pressure going from a 5-30 to a 20w-50. After the clean out, I would go a 15W-40 in winter and the 20W-50 in summer. I live in a climate similar to yours, and would never use a 5W-anything. I might even suggest that this light oil caused premature bearing wear (me puts on fireproof suit}. I mean 83,000 isn't a very high mileage for your engine. Dave

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That's exactly what I was thinking!

 

[outrun]

On an old tried and true PC1 Police LT1? After reading all the incites of our Aussie members a XXW50 weight is not necessarily the worng or improper weight for your car...seasonaly speaking. Otherwise 10W40 or 10W30 for winter depending on temperature will be fine. Are you planning to Reman your engine and transmission? If so perhaps 10W30 or 40 year round would be fine then too. There is just this mentality against heavy oils here sponsored in part by uncle same and the auto makers. Now on to me perhaps i too will be brave and try Mobil 1 15W50 this summer. Let's see if i can follow my own advice.

 

[RDW]

"Huh, how can you have $13 G's in a "free" car??" Here's How: Serpentine Belt BYA Gas Shocks (4) PCV Valve Rubber Floor Mats Replace Both Passenger Side Windows Wheel Center Cap (1) 9c1 Wiper Blades (2) Home Plate & First Base Delete K & N FIPK Steering Wheel Cover Replace All Fluids Oil Pan Gasket Valve Cover Gaskets Steel OIL Cooler Lines Transmission Service. Replace Filters Replace All Light Bulbs Paint & Body Work Black Body Molding Hood (no emblem) Settina Push Bar Install Center Console Install Lock Box Radiator Flush (remove Dex-Cool) MSD Coil Water Pump Oil Pressure Sending Unit Pinion Seal Carbon Clean Process & Clean Throttle Body Fuel Filter Throttle Body Bypass Brake Switch Dash Cover Window Tint (Rear 5 Windows 20%) Driver's Side Seatbelt Lower Seatbelt Panel (driver's side) A/C Service Stealth Brake Bolt Battery (AC Delco 7 Year) Complete Transmission Re-Build 180 degree Thermostat Remove Excess Wiring Bundle (Cop Stuff) Spark Plugs (8) O2 Sensors (4) Opti Distributor Cap & Rotor EGR Valve Idle Speed Controller Knock Sensors (2) Checked ALL grounds Did "something" with one , or more Injectors Separated & Checked ALL Wires in Engine Wiring Harness New PCM & Re-Flash Troubleshoot & Repair Engine Wiring Harness Install "Kill" Switch Change Oil & Filter (Kendall 20W50) Auto RX Treatment Fix Horn Replace Starter Bank 2 Cat Converter PCM Re-Flashed Fans & Fan Curcuits Tested (No Problems) RPM 20" Loback Mufflers W/ Braided "H" Pipe

 

[outrun]

Sounds like an all out restoration to me Your my kind of owner, not only are you thoroughly going through the maintence checklist of systems. Your also buying high quality parts to do it right the 1st time. Hmmm...maybe I missed it..are you planning on new Upholstery too Post some pics....this should be an interesting project. I bet you spent at least 3-4,000 on the clear coat-base coat paint job too

 

[Patman]

I think 20w50 is too thick for the LT1. My LT1 really seems to like a thick 30wt. I believe that anything between 12 to 14 cst at 100c is pretty much ideal for the LT1. I drive my LT1 hard and with a 12.2 cst oil I get 1ppm/1000 miles for my lead content. So this shows to me that the viscosity choice is correct.

 

[heyjay]

quote:

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Originally posted by Patman: I think 20w50 is too thick for the LT1. My LT1 really seems to like a thick 30wt. I believe that anything between 12 to 14 cst at 100c is pretty much ideal for the LT1. I drive my LT1 hard and with a 12.2 cst oil I get 1ppm/1000 miles for my lead content. So this shows to me that the viscosity choice is correct.

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We're talking about the Bay Area, not Canadian climate. I have an Aunt and Uncle in Sant Rosa, about an hour north of this fellow, and all they run in their car and truck is Mobil 1 15W-50. Their idea of a "cold" winter morning is +30 F. Most of the water pipes and plumbing is outside the house. That's something I could only dream of. Jerry

 

[heyjay]

quote:

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Originally posted by RDW: "Huh, how can you have $13 G's in a "free" car??" Here's How: Serpentine Belt BYA Gas Shocks (4) PCV Valve Rubber Floor Mats Replace Both Passenger Side Windows Wheel Center Cap (1) 9c1 Wiper Blades (2) Home Plate & First Base Delete K & N FIPK Steering Wheel Cover Replace All Fluids Oil Pan Gasket Valve Cover Gaskets Steel OIL Cooler Lines Transmission Service. Replace Filters Replace All Light Bulbs Paint & Body Work Black Body Molding Hood (no emblem) Settina Push Bar Install Center Console Install Lock Box Radiator Flush (remove Dex-Cool) MSD Coil Water Pump Oil Pressure Sending Unit Pinion Seal Carbon Clean Process & Clean Throttle Body Fuel Filter Throttle Body Bypass Brake Switch Dash Cover Window Tint (Rear 5 Windows 20%) Driver's Side Seatbelt Lower Seatbelt Panel (driver's side) A/C Service Stealth Brake Bolt Battery (AC Delco 7 Year) Complete Transmission Re-Build 180 degree Thermostat Remove Excess Wiring Bundle (Cop Stuff) Spark Plugs (8) O2 Sensors (4) Opti Distributor Cap & Rotor EGR Valve Idle Speed Controller Knock Sensors (2) Checked ALL grounds Did "something" with one , or more Injectors Separated & Checked ALL Wires in Engine Wiring Harness New PCM & Re-Flash Troubleshoot & Repair Engine Wiring Harness Install "Kill" Switch Change Oil & Filter (Kendall 20W50) Auto RX Treatment Fix Horn Replace Starter Bank 2 Cat Converter PCM Re-Flashed Fans & Fan Curcuits Tested (No Problems) RPM 20" Loback Mufflers W/ Braided "H" Pipe

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Wow, that's more of a frame-off restoration! Bypassing the heated throttle body (Loop the coolant hoses) sure does gain power. I almost cry that I can't pull that stunt here, as my throttle body would ice up. I hope your trans rebuild didn't cost more than the new Pace Performance crate 4L60E. I personally don't bother with rebuiding things anymore as the crate parts are cheaper (Usually) and carry warranty. Yank out the old part, put in the new part, and return the old part for the Core Charge credit. Those O2 sensors are $$$ from the dealer. I've used NAPA and the box is labeled Neihoff. The sensors are a fraction of dealer cost and appear to be Made In Germany Bosch O2 sensors. Jerry

 

[VaderSS]

quote:

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The last model Chevy Caprice police package came with 4L60E transmissions and LT1 motors. The instrument cluster had a vacuum flourescent digital speedometer, withanalog tach , fuel, temp, and oil pressure.

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No tach, and had a volt meter, but otherwise correct. 94-96 Caprices, 9C1 or otherwise, never came with a tach.

quote:

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Bypassing the heated throttle body (Loop the coolant hoses) sure does gain power. I almost cry that I can't pull that stunt here, as my throttle body would ice up.

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We have members in Alaska that have done the TB bypass. Not ONE instance of icing. The TB serves as a heat sink to condense steam from the heads, not as a deicer. It is of most use in EXTREMELY hot climates, not cold ones. [ March 09, 2004, 12:01 PM: Message edited by: VaderSS ]

 

[Patman]

quote:

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Originally posted by heyjay:

quote:

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Originally posted by Patman: I think 20w50 is too thick for the LT1. My LT1 really seems to like a thick 30wt. I believe that anything between 12 to 14 cst at 100c is pretty much ideal for the LT1. I drive my LT1 hard and with a 12.2 cst oil I get 1ppm/1000 miles for my lead content. So this shows to me that the viscosity choice is correct.

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We're talking about the Bay Area, not Canadian climate. I have an Aunt and Uncle in Sant Rosa, about an hour north of this fellow, and all they run in their car and truck is Mobil 1 15W-50. Their idea of a "cold" winter morning is +30 F. Most of the water pipes and plumbing is outside the house. That's something I could only dream of. Jerry

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That analysis in my car that I'm referring to was in the end of summer up here though, and our temps are not that much cooler than his will be.