Thoughts on a 5.3L, Oil Life monitor, and Synthetic?

[GM Guy]

Hey all,

Wanted to get some other opinions regarding the family Tahoe.

2001 Tahoe, 5.3L auto 4wd.

Mostly runs around (we live 10 miles from town, so no trip is a short trip), does tow occasionally, and when it does it can be for long distances, last one was a car trailer hauling a 2500 lb combine header on it for 1000 miles, when towing, never ran hard, try to keep it 70 mph or less, tow haul on, etc.

We are running full synthetic 10w30, I cant recall which, either Valvoline or Mobil 1.

What is everyone's thoughts on the Oil Life monitor in regards to synthetic?
I am aware it is calibrated to non-synthetic, but what I am wondering is for actual oil life, can a guy run till the Oil Change light comes on, change filter, top off oil, and reset the light, and then change it the next time the light comes on?

I should probably just take an oil sample to find out for sure, but wanted to see what other's opinions are.

Thanks!

 

[schiker]

Probably would work fine if you consider synthetic should go at least twice as far as dino oil.

That era oil life monitor is just a revolution counter with some multipliers for temperature and engine conditions vs fuelrate.

I keep a little book and tally how much fuel I pump into tank and change oil after 200 gallons of fuel as soon as I can. I figure its the fuel (blowby) that contaminates oil and a how much fuel you burn is a good indicator of how hard you are pushing at least more so than just miles driven. It should work out about right if its like this....

Working hard,
11- 13mpg - 200 gallons is 2,200-2,600 miles

Easy driving
17 mpg at 200 gallons is 3,400 miles

 

[WarWagon]

You run full "synthetic marketing term" for oil that has better heat tolerance and other proprieties when working hard. Thus the entire goal is the extra reserve when SHTF while towing because all it has to do to be worth it is prevent the expensive piston scuffing a little longer sometimes. Oil sludge is still a problem today on some engines more than others. MPG increase and other benefits are all good with the last thing to reach for is longer drain intervals.

Most overlook the oil filter's ability to take this longer interval without disintegrating or clogging up. Nevermind the "we don't give a s#it" quality of some decorative non-functional expensive filters I have seen where you are running with a torn pleat or pleat that isn't glued at all. Spend the money to obtain a good oil filter as the Ecore ACDelco and OCD bottom of the "how cheap can we make this?" barrel isn't the best choice for long drain intervals. IMO Tear-O-Lators are only good for around 3000 miles before they tear a hole in a pleat. Amsoil filters *Cough Cough* site vendor here @LanduytG *cough* and off the generic parts store shelf WixXP are examples of a filter marketed and designed for long drain intervals. (Seriously with 2500 mile oil changes required by the book and "pushing it" at 3000 miles you bet I question the capacity of a 6.5 oil filter getting soot clogged while being broiled on high! I have seen some awful cut open filters.) There is a good reason people look for and use larger oil filters than the OEM gave em!

Towing, no matter the weather, is working hard as seen by fuel consumption. Fuel burned mean contaminates in the oil and is one of many factors that bring engine oil to the end of it's useful life. This contamination brings oil to the end of it's life no matter what kind it is. Sudden death of engine oil is by overheating and IMO one factor the oil life monitor considers.

Biased on our fleet experience over a decade ago, largely on the 4.3 V6, the oil life monitor is fairly accurate needing oil changes around 5,000 miles and UOA backed this up.

Same accuracy for our LMM of just under 10K on easy use and less for hard towing. Speaking of Diesel oil Shell Rotella has a higher TBN in the regular oil than their synthetic due to fleet manager demands because they won't run a higher cost synthetic unless they have too. This example is one where the synthetic may have a lower number of miles available before one marker indicates a need to change it.

The downside is contamination could, and did, set off the low oil pressure stop engine alarm that the OLM did not and could not act on. Thus UOA is a useful tool in addition to the Oil Life Monitor.

GM has recalled some vehicles due to excessive timing chain wear and the fix is more frequent oil changes programmed into the OLM. So the rumor that it's conservative isn't always true.

Best way to know when to change the oil is stick a tube down the dipstick, suck some oil out, and send it to the lab. Then establish a baseline for the vehicle with the better oil. Then you can ignore the Oil Life Monitor by monitoring it yourself with better tools than the OLM has. You can also see intake dirt leaks, impending engine failure (That's always a fun $Fing$ call from the lab!), and more for less than $10.00 a pop.

 

[Will L.]

Everything above with a couple options.
Most people wont do the uao even though they pay for themselves. If you fall into this category, get the little tester Leroy sells. All the 3rd party and especially int on those showed they are pretty accurate. Obviously you cant squeeze out every mile with it, but better than nothing at all.

All engines benifit from a centrifuge on the oil system.

Quality air filter is just as important as oil filter. Letting it suck in the fine dust straight to the cylinders and the silicone(abrasive part of dirt) goes into oil while sanding away cylinder walls.

My experience has been the 6.0 does just as good mpg if you keep your foot out of the last 20% when empty, and does better mpg when towing or loaded heavy. Not taking away from the 5.3, just 6.0 does a hair better.

 

[GM Guy]

I guess I forgot to add, old man can still milk 12 mpg with that 2500 lb header on the car trailer, so oil is under little strain.

So what is the most recommended oil analysis place that is a good value? If there is any sort of multi-sample discount that might be a factor too.

I might think about adding bypass filters to stuff and going to extended intervals, as IMO our operation could benefit from it, since moderate loads, conservative driving, and long distances are probably the most extended interval friendly.

 

[JayTheCPA]

Seeing as you are in the 'fleet' territory, might consider contacting the labs to see what they have in terms of bulk pricing for analysis kits. Even buying 10 packs will save some money.

Toward labs, the ones I read about most are Blackstone and Oil Analyzers (which looks like they are using Polaris Labs).

Am with the others about getting UOA first to verify what the on-board system is reporting. For example, have a 10 year old SOB hybrid that will happily go 5K on the oil based off its computations, except UOA has me changing every 2,500 due to to very low pH.

Regarding bypass filters, definitely worth the money as they saved my P-400 from severe metal contamination within its first 500 miles. There was damage to the crank and oil pump, but the filters prevented any further damage.

And by the way, even if UOA supports extended drain, I still change the filters based on mileage per the normal oil drain cycle.

 

[WarWagon]

Not a fan of Blackstone, but, I get a box of 8 (or 10) sample packs from a local lab http://www.laboneinc.com/ and depending on options around $10 a pop. Lab reputation and quality is important to getting useful results. For example flagging coolant on a manual transmission you would think is NUTS until you find out how badly the engine in front of the MT blew up contaminating the transmission through the vent. Only because you trust the lab and results.

In addition to UOA I also cut open used oil filters to see if I can read part numbers (in the metal debris it caught) let alone to see if the filter did it's job. I use the CAT tool even on the "isn't that cute" little filters... https://parts.cat.com/en/catcorp/175-7546

@JayTheCPA ever look into other oils or operating conditions why the pH is dropping so fast? Normal for this vehicle?

 

[JayTheCPA]

. . . ever look into other oils or operating conditions why the pH is dropping so fast? Normal for this vehicle?

It is a hybrid, and Yes apparently this is common. Source issue is fuel contamination. My read is that the engineers figured that a motor-is-a-motor and did not do anything different in terms of the rings to handle frequent idling and start-stop cycles.

Took the car to the local independent 'expert' and asked for an opinion on how to address the fuel-in-oil contamination. When I showed the UOA report and my concern, the shop owner had no clue what a UOA was, nor what I was worried about, and told me to just change the oil every 3K - 5K miles like he told all his other customers to do. So, am figuring that just replacing the oil a lot more frequently in that car is a lot less expensive than tearing apart the motor to fix the manufacturer's design mistake.

 

[btfarm]

To answer the original question... I run M1 synthetic 5w30 in the 07 5.3 Tahoe. By the time the oil life monitor hits near zero it's usually down about a qt anyhow so I change it. Usually it's near 4000 miles. I'm sure I could run it longer without worrying but can't bring my old self to do it.

 

[tanman_2006]

I've always ran 10k on the newer gas engines if they are mostly highway and used the top quality M1 with a wix xp.

If I use it has like farm truck I do 5k changes.