'23 GMC 6.6L GAS - Oil Analysis and OCI Questions

[SoCalAngler]

I'm new at this oil selection/analysis, as I have not purchased a new truck in many years where I can service and record from new.
I want to take great care of my investment, as best I can:

2023 GMC Sierra 3500HD; 6.6L GAS/6 Speed Trans; 4x4; Crew Cab; Short Bed

After doing some reading on the subject, I believe it's probably most important to determine best OCI mileage/schedule based on oil analysis... then use the results to determine what that OCI mileage schedule should be. I plan on using using readily available D1-G3 5W-30.

I would like to know more about oil analysis....

• At what mileage should analysis begin (considering a new truck)?
• At what mileage intervals?
• What key components are important to monitor in an analysis?
• Is there a "break in" mileage that is used as a base line when beginning an analysis to determine best OCI?
• How many analyses are needed to determine a base line?
• Since there are variables in miles accumulated between analyses (towing, not towing, city, hwy, fuel brand/octane, etc.), how is the OCI determined based on these varying analyses?

Now, since my first oil change will be at 500 miles (next week) and I'll be using M1 AFS (D1-G3)....

1. Would an oil analysis be worthy at the 500 mile oil change?

2. What would be the analysis schedule/interval miles to ultimately determine best OCI?

Perhaps I'm way overthinking this.... or I have missed 1 or 100 other steps!....

Thanks!

 

[AZjeff]

1. No
2. You're going to be told to wait XX miles until break-in is done before testing.

I have the same engine and so far 75% miles are towing so I'm taking the easy route, 5k OCIs with Quaker State FS 5w-30. Just went over 20k on the truck, might do a UOA @ 25k.

 

[wpod]

What are you expecting to gain from am oil analysis program. A 500 mile uoa will show lots of break in metals. I would wait for a couple of oil changes unless you expect a problem . More load on an engine will show more wear .Those are nice trucks and engines. The best thing to do is have clean lubricants. Change the oils regularly.

 

[SoCalAngler]

1. No
2. You're going to be told to wait XX miles until break-in is done before testing.

I have the same engine and so far 75% miles are towing so I'm taking the easy route, 5k OCIs with Quaker State FS 5w-30. Just went over 20k on the truck, might do a UOA @ 25k.

Did you perform any oil changes prior to recommended first at 7500 miles?

 

[AZjeff]

First one at 1000 then at 5k,10k, 15k etc. The OLM says I'm changing out good oil. Don't care, towing in hot weather and lots of elevation changes.

 

[SoCalAngler]

First one at 1000 then at 5k,10k, 15k etc. The OLM says I'm changing out good oil. Don't care, towing in hot weather and lots of elevation changes.

Sounds like we have similar uses....towing a TT in 100F+ temps, towing my fishing boat weekly, plus all other common truck uses! When I purchased....I drove the truck home 150 miles from dealer in 119F!!

 

[64bawagon]

I have had 2 of these truck, a 21 and a 24. I dont plan on any analysis until I get at least 20k on the 2024.
The OLM on these trucks has been established from a mountain of testing by GM. My opinion is that they have already done the work to find the data. I typically change mine around 20% because of the towing I do with it. As long as youre using a proper spec oil and a decent filter I see no need to worry unless the truck exhibits symptoms of a problem.
In the end, its your truck and your money and you should do what makes you happy.

 

[4WD]

I have had 2 of these truck, a 21 and a 24. I dont plan on any analysis until I get at least 20k on the 2024.
The OLM on these trucks has been established from a mountain of testing by GM. My opinion is that they have already done the work to find the data. I typically change mine around 20% because of the towing I do with it. As long as youre using a proper spec oil and a decent filter I see no need to worry unless the truck exhibits symptoms of a problem.
In the end, its your truck and your money and you should do what makes you happy.

My newer Tahoe is the 1st I put on a dealer service/extended warranty plan and they want to do oil at 20% OLM - which is about where I always do my own changes …

 

[SoCalAngler]

I have had 2 of these truck, a 21 and a 24. I dont plan on any analysis until I get at least 20k on the 2024.
The OLM on these trucks has been established from a mountain of testing by GM. My opinion is that they have already done the work to find the data. I typically change mine around 20% because of the towing I do with it. As long as youre using a proper spec oil and a decent filter I see no need to worry unless the truck exhibits symptoms of a problem.
In the end, its your truck and your money and you should do what makes you happy.

Thanks for the info.

What was the reason you went from a relatively new '21 to a '24? The '21 is a very nice truck.

 

[SoCalAngler]

My newer Tahoe is the 1st I put on a dealer service/extended warranty plan and they want to do oil at 20% OLM - which is about where I always do my own changes …

20% OLM sounds like a reasonable spot for a warranty plan

 

[Tachyon]

First off, kudos to you for wanting to take meticulous care of your new truck investment. Proper maintenance, especially in the form of oil changes and analysis, can indeed significantly extend the lifespan of your vehicle and ensure it performs at its best. Let's delve into your questions one by one.

Oil Analysis Basics
Oil analysis gives you a detailed look at the health of your engine by examining the contaminants and chemical makeup of your oil. The objective is to catch any potential issues before they become bigger problems and to gauge how well your oil is performing.
When to Begin AnalysisFor a new truck, it's ideal to do an initial analysis fairly early to ensure there aren't any anomalies from the factory, such as metal shavings or contaminants.

1. Is an oil analysis worthy at the 500-mile oil change? Yes. The first oil change is crucial because it often contains more contaminants from the manufacturing process.
2. Analysis Schedule/Interval: A popular regimen is to perform the first analysis at 500 miles, then at 3,000 miles, and then every 5,000 miles thereafter, especially if you are trying to establish a solid baseline. After several consistent reports, you can extend the interval based on the health of your engine and the results of the analyses.

Key Components to Monitor in Analysis

1. Wear Metals: This includes iron, copper, chromium, aluminum, and others. An increase can indicate abnormal wear.
2. Viscosity: Measures oil's resistance to flow. If it's out of spec, it can indicate contamination or oil breakdown.
3. Total Base Number (TBN): Shows the amount of active additive left in your oil.
4. Water and Coolant Contamination: Presence can lead to rust and other major issues.
5. Fuel Dilution: Fuel entering the oil can reduce its viscosity, leading to increased wear.
6. Dirt and Silicon: Can cause abrasive wear.
7. Soot: In diesel engines, this indicates combustion inefficiency.

Break-in Period & Baseline Analysis:
The "break-in" period for most vehicles is typically the first 500 to 1,000 miles. The analysis done post this period helps establish a baseline. Ideally, 2-3 analyses done during the early life of the vehicle should give you a clear baseline.

Determining OCI with Varying Analyses:
Variability in driving conditions indeed affects oil life. If you alternate between heavy towing and casual city driving, your oil might degrade at different rates. Regular analysis helps you gauge the influence of these variables. If you tow heavily for a month and analysis shows rapid oil degradation, you might decide to shorten your OCI for similar future periods.

Conclusion:
You're not overthinking this; you're being proactive. Consistent oil analysis can help ensure your GMC Sierra remains in top shape for years to come. Start with that 500-mile oil change and analysis, then establish a regular schedule based on the results and your driving habits. As you accumulate data, you'll gain a better understanding of your truck's specific needs and the best OCI for it. Safe travels and happy driving!

 

[SoCalAngler]

Thanks Tachyon....all questions answered and very thoroughly!!!

 

[64bawagon]

Thanks for the info.

What was the reason you went from a relatively new '21 to a '24? The '21 is a very nice truck.

Some fool offered me an obscene amount of money for my 21. The truck ran flawlessly and I never had to take it in for anything during the 2 yrs I had it. It was sitting in my barn in February all clean and shiny while it snowed outside, I didnt need it until late summer AND they build new ones all the time about 12 miles up the road AND I get the GM employee discount through family. So I added a couple of options I wished I had bought on the 21 plus a couple of items that were now standard and this is the result.

 

[tnt_motorsports]

My son bought a 2023 Ram in May. He asked me relatively the same question you have asked @64bawagon

I recommended he change his oil at 2k miles, 5k and 10k. I told him to hold off on a UOA until the 10k change. Not saying this is a perfect plan but I think doing a UOA any earlier will probably not give you a lot of insight.

Just my $0.02