Oil consumption report

[mrrsm]

Thanks for the timely update...

I think I understand... you mean they are using kind of a "Thermister" technique of capturing electrical resistance and running the differences against a known look-up table to make these variables register on the Needle Gauge? Is there a convenient and available factory pre-plugged oil galley on the GM Atlas 4.2L Engine that can be exploited using a Copper Tube-To-Analog Oil Pressure Gauge and perhaps mount it somewhere in the engine compartment to take the actual dynamic pressure?

 

[C-ya]

I have 166,590 miles as of last night. I used to change the dino oil in my '98 GMC with a 4.3L V6 every 4K, whether it needed it or not. It used a quart in the interval. I bought that truck with 140K on it and sold it with 243K, still running strong. The TB is only going about 5,500 miles between oil changes (or less in the winter due to idling) via the OLM and synthetic oil. I agree about the blow by, especially since this engine is (was) a DOD/AFM engine. I'm sure the damage is done. I'll switch to a 4K mile interval after this one and see if I notice anything different.

My oil pressure is 40+ at idle. I had to change the oil pressure sending unit last week, and while there, I cleaned the filter.

 

[littleblazer]

Thanks for the timely update...

I think I understand... you mean they are using kind of a "Thermister" technique of capturing electrical resistance and running the differences against a known look-up table to make these variables register on the Needle Gauge? Is there a convenient and available factory pre-plugged oil galley on the GM Atlas 4.2L Engine that can be exploited using a Copper Tube-To-Analog Oil Pressure Gauge and perhaps mount it somewhere in the engine compartment to take the actual dynamic pressure?

There is a plug by the oil filter iirc. It's around here somewhere. It's purpose is a test port. But it is some weird metric thread pattern that is annoying to find.

 

[mrrsm]

Good Lead... Thanks LB...

 

[mrrsm]

I have 166,590 miles as of last night. I used to change the dino oil in my '98 GMC with a 4.3L V6 every 4K, whether it needed it or not. It used a quart in the interval. I bought that truck with 140K on it and sold it with 243K, still running strong. The TB is only going about 5,500 miles between oil changes (or less in the winter due to idling) via the OLM and synthetic oil. I agree about the blow by, especially since this engine is (was) a DOD/AFM engine. I'm sure the damage is done. I'll switch to a 4K mile interval after this one and see if I notice anything different.

My oil pressure is 40+ at idle. I had to change the oil pressure sending unit last week, and while there, I cleaned the filter.

243K and still humming along is a damned fine outcome! Combustion engines invariably burn a few drops of oil as a matter of course and the Brand New Service Manuals all have big bright warnings for the New Owner that checking the Oil Level frequently... even on a BNV (Brand New vehicle) is the best habit to adopt. I bought my '02 IN 2002 with just over 42K on in it and for the life of me, I've no idea how anyone could have driven nearly double the circumference of the earth in only six months! And so I concur with your idea that it is always a crap-shoot as to how well behaved the prior owner(s) were regarding regular maintenance of the vehicles they sell. Its a rare and fortunate buyer who pulls the dipstick and see a beautiful, honey golden slip of oil that is so clean, you can see the warning level hash lines cut into the metal measuring stick. Whenever I have done that... the dipstick(s) were invariably bone dry.

Regarding the mysterious loss of oil...With the exception of the TB Atlas rear crankshaft seals, most engines eventually lose an amazing amount of oil to dynamic leaks from those seals. Last year, I changed out the HUGE CS Seal when I put in a new transmission and I was amazed to see that not one smidgen of oil was present there around the old one after 240 K... ; sterling testimony to the value of the Wide, Double Inner & Outer facing sloped lip design that prevents it from ever grooving the crankshaft and also being made of durable PTFE.

Contrasting that is my '93 Z-28 with the Corvette LT-1. I bought that car brand new back in 1993 and even with my fetish for oil and filter changes on schedule and considering that even after all this time, it only has 98K miles accumulated, it literally paints the 4L60(no "E" in the '93) transmission fluid pan from from front to back with Mobil1 from the rear crankshaft seal not holding the stuff in. Go figure...

 

[dporter]

I thought this thread was for the 5.3 V8 so here is my input. 159500 miles on my 07 Denali. Was using a quart of 5w30 every 2k miles depending how I drove it. I disabled the DOD by unpluging the brake booster and I got 3800 before I added a quart. Getting 18 -18.5 mpg which is about 1-2 mpg less than before the delete. I'm going to run with the DOD disabled for a while to see if the oil consumption stays the same and ignore the engine light.
Dave

 

[Reprise]

My '03 Voy has the LM4 5300, so no DOD. With about 135K on the clock (I got it with 128K), it doesn't seem to be using oil, and doesn't have any visible leaks. The one thing I did note, however, is how sensitive it is to degree of incline / decline when checking the oil level. When I first got it, I thought it used a quart in less than 1000 miles. Turned out the slope of the driveway (facing 'upward') was enough to make it show 'low' by a quart. Since then, I'm more cognizant of trying not to be on a grade when I check it (or accounting for it when I am). Also, since I don't drive the truck often, I tend to check it after it's been sitting for (at least) a day, so as to account for any issues draining back into the crankcase.

 

[Mooseman]

I disabled the DOD by unpluging the brake booster

Just to clarify for anybody reading this, it's unplugging the vacuum sensor on the brake booster. I did it for a while until I got DOD tuned out.

 

[C-ya]

My trip to north GA over the Christmas holiday was into a headwind most of the trip south. I also had a couple hundred extra pounds in the back that I dropped off near Knoxville, TN, first and spent the night in Pigeon Forge. Drove over the mountain into NC through Cherokee and Franklin to get to my dad's in north central GA. Added a quart of oil there. I added another quart in Chattanooga on the way back home after a few days/miles in the north GA mountains/foothills. We spent the night there and visited the aquarium. I added another quart when I got home. Total trip mileage was about 1,635 miles. I changed the oil a week before we left, and it now is now down to 80% on the OLM. Best average fuel mileage was 17.4 mpg and that was on the way home.

I think I will change the oil only (drain and fill) since it is pretty fuel soaked and then see how it goes for the next 4K miles since there will be a lot of winter idling.

 

[mrrsm]

There is a plug by the oil filter iirc. It's around here somewhere. It's purpose is a test port. But it is some weird metric thread pattern that is annoying to find.

How Ironic that you just posted your Oil Comsumption Progress... I only just got this equipment to follow up on the suggestions about determining the ACTUAL Oil Pressure at various RPM settings vs. the Digital Dashboard Gauges. When I finally get the Aluminum Engine Head R&R completed on the "$85,000.00 Job" done, hopefully sooner than later... I'll search out the Oil Pressure Fitting Location area you mentioned and figure a way to view this new OP Gauge in the CAB area. In a worst case scenario... I'll mount it in the Engine Compartment in plain view.

Your decision to change the now fuel infested Engine Oil... is EXACTLY what needs doing after long hauls ...it will make a big difference in keeping the engine going much longer.