07 Chevy Silverado 8.1 welding truck

[TXHunter]

Brother in the law is a pipeline welder, and just acquired a new heavy duty travel trailer. On his most recent trip from South Texas up to Wyoming pulling the travel trailer, and welder/welding bed he became concerned with oil pressure (TT is about 15K 5th wheel). Engine has about 120K mile and typically runs Rotella 10w-30, but was using Valvoline 10w30 on this run (all conventional). At 55mph & 1800rpm he was running about 25 on the oil pressure gauge. He is used to seeing it much higher on this truck, and has a farm truck with the 8.1L that also runs with oil pressure much higher.

His concern is being stranded in his work truck 1000's of miles from home, so he is thinking is time for an engine rebuild. I've tried to get him to do an oil analysis on the engine but I'm not sure he is interested. Would a switch in oil/viscosity alleviate the lower oil pressure or is it really time to start budgeting for a rebuild?

 

[expat]

The old standard was 10 psi per 1,000rpm

There is nothing wrong with his engine. Perhaps some heavier oil would make him happier?

 

[Brons2]

I'd switch back to rotella before doing anything as drastic as rebuilding the engine.

 

[dave1251]

The simplest thing to do is change the oil filter to see if this caused the decrease in oil pressure.

 

[NHGUY]

5 years old and needs a rebuild? Something is wrong there.

 

[eljefino]

First thing to check would be the sending unit, ie put a good mechanical gauge on it. Agree with the oil analysis in case there's been a long term intake air leak letting unfiltered grit grind away inside the engine.

Does that truck have an oil temp gauge? Maybe add one?

 

[EricF]

I would be switching to a synthetic, Redline or Amsoil to handle the beating the engine takes.

 

[AlienBug]

Long highway run through mountains towing 15,000 pounds = oil got a little warm. Tell him you'll take it off his hands.

 

[Rob_Roy]

Originally Posted By: eljefino
First thing to check would be the sending unit, ie put a good mechanical gauge on it. Agree with the oil analysis in case there's been a long term intake air leak letting unfiltered grit grind away inside the engine.

Does that truck have an oil temp gauge? Maybe add one?


Good advice on the mechanical gauge. I suspect the oil got hotter than he is used to, and he happened to notice the lower reading on the gauge. Not to mention he went from a HDEO to a PCMO 10w30...I bet the Rotella is slightly thicker at operating temp.

 

[Donald]

I would go back to Rotella. Check with mechanical gauge to calibrate the dash gauge. Replace the sender if the dash gauge is off. Replace oil filter. Next would be to replace the oil pump, maybe the pressure relief spring is tired or the pump is defective.

Next pull the pan and use plastigauge on the bearings and see if its within specs.

Just don't jump into a rebuild unless the engine seizes.

 

[JimPghPA]

Go back to Rotella, and a new oil filter. Heck, it could be a bad oil filter is the reason the pressure is low.

 

[AlienBug]

Originally Posted By: Donald
I would go back to Rotella. Check with mechanical gauge to calibrate the dash gauge. Replace the sender if the dash gauge is off. Replace oil filter. Next would be to replace the oil pump, maybe the pressure relief spring is tired or the pump is defective.

Next pull the pan and use plastigauge on the bearings and see if its within specs.

Just don't jump into a rebuild unless the engine seizes.


Or he could just keep driving because his engine is fine.

 

[JimPghPA]

BTW, many people have found that as they rack up the miles, changing to a higher viscosity oil keep the engine running well because the gap between parts becomes somewhat more with use.

Maybe time for Rotella 15W-40 in the summer and Rotella T6 5W-40 in the winter.

 

[hattaresguy]

I wouldn't worry about it. Unless he did some super extended oil changes in the last 125k miles that big block should have a lot of life left.

1. What are GM's specs in regard to oil pressure with that motor? If its within spec its fine.
2. You need to hook up a real oil pressure gauge to see if that dash gauge is accurate. A lot of times they are not.
3. Change the oil because maybe the filter went bad, it happened to me. While your doing it send a sample out to the lab. If the main bearings are wearing enough to lose oil pressure your going to be seeing lots of copper.

 

[TXHunter]

Sounds like the consensus from the group is change the oil & filter, and drop the valvoline conventional in favor or Rotella or some other HDEO.

Changing from a 10w30 to either 5w40 or 10w40 will most likely provide the higher oil pressure he wants to see. In his application, are there any down sides to switching to a higher vis oil?

 

[Rob_Roy]

Another question - Did your BIL check the oil level after this event? The 8.1L engines are known to consume some oil, especially when worked hard.

 

[afoulk]

Originally Posted By: Rob_Roy
Another question - Did your BIL check the oil level after this event? The 8.1L engines are known to consume some oil, especially when worked hard.

didnt they have piston issues?

 

[TXHunter]

Great question, I'm not sure the oil level was checked yet. He said he had an oil change done right before leaving and the trip put about 1200 miles on the truck. I'll check with him and see, and I'm going to try to push again to have an oil sample done.

 

[Rob_Roy]

Originally Posted By: afoulk
Originally Posted By: Rob_Roy
Another question - Did your BIL check the oil level after this event? The 8.1L engines are known to consume some oil, especially when worked hard.

didnt they have piston issues?


I don't remember the details, just that three co-workers of mine complained of oil consumption with their 8.1L engines. One was told that the engine had to consume over 1 quart of oil per 100 gallons of fuel consumed to qualify for warranty work.

 

[c502cid]

Originally Posted By: JimPghPA
BTW, many people have found that as they rack up the miles, changing to a higher viscosity oil keep the engine running well because the gap between parts becomes somewhat more with use.

Maybe time for Rotella 15W-40 in the summer and Rotella T6 5W-40 in the winter.


As owner of my second 8.1, the plan above has worked absolutely great for me. Although I've heard of 8.1's using oil, mine both might go through a quart, quart and a half between 6000-8000 mile OCI's.