UOA Motul 8100 5W30, 01 Silverado 2500HD 11k mi

[CentAmDL650]

Ran this Motul 8100 5W30 for a little over 11,000 miles, using a Wix filter. Early consumption was at about 1 qt / 4000 miles, but the most recent checks for makeup oil on this OCI got to more than 1 qt / 2000 miles. I thought I would mention my plan to correct this with a short MMO cleaning interval to Blackstone, and feel quite puzzled by their response in the comment section. They as well as anyone should know that rings do not have to be worn to stick or allow increased cosumption.

I'm questioning the validity of the insolubles % measurement also, as the VOA for Motul 8100 Econergy 5W30 shows 9.8 cSt @ 100°C - my sample viscosity has increased almost 1 cSt over the OCI, and I think that is soot thickening - possibly even the onset of sludge formation.

 

[CentAmDL650]

For reference, here's the VOA of the Motul 8100 5W30 that I used in my last OCI, shown in the UOA above.

 

[slo town]

OP, your latest OCI indicates about 3200 miles per quart used. This on a 15 year old truck with 124k miles.

Why do you consider this a problem that needs some kind of treatment?

Scott

 

[mjoekingz28]

Is this the iron head?

 

[CentAmDL650]

It's an iron block with aluminum heads LS1, order code LQ-4.

While the average was 1 quart per 3200 miles, it started the OCI at less than 1 quart per 4000 but increased to 1 qt/2500 8.7k mi in, and by my last check at 10.3 k mi in, it was around 1 qt/1800 mi. If a cleaning gets me back to 1 qt/ 4500 mi, the MMO will have paid for itself several times over.

The Motul 8100 goes for about $9.50 / quart delivered, IIRC. With a 6 qt sump capacity, a 1 qt/1800 mi 11k mi OCI costs about $.01003 per mile ($110.33); a 1 qt/4500 mi 11k OCI costs $.00686 per mile ($75.46), which is a savings of $34.87, enough to pay for 5.4 quarts of MMO.

Anyways, I was most displeased with the KV100 increasing almost 1 cSt due to soot thickening and (probably) oxidation. I realise most group III oils would have already given up the ghost long before 11k mi in this engine, but I thought a group IV / V mix would have been good to go without varnishing the OC rings, especially since my OCD preoccupation with oil consumption has me checking the dipstick every other weekend, and never adding more than 12 oz at a time.

I'm thinking of changing my OCI to 8k, maybe I'll get 3 OCIs before the rings gum up again and it needs another cleaning cycle.

 

[mjoekingz28]

I have the LQ4 as well.

Ok, 99 & 00 were the iron heads.

Don't take my word for it, but I think ANY engine with ANY oil will eventually burn off if left in too long.

That being said.......

If yours has the oil change reset message, are you resetting it and running it twice.


Why not just change when the manual says?

I think for my 03 is to follow the message, but never to exceed one year or 10,000 miles.

If you are driving a lot-maybe 7500 on top shelf oil for all highway driving.

3000 or a year if rarely driven.

5-6 on semi-syn for daily driver type duty.









What is it about oil that begins to burn on extended drains?

Is it gumming up the works? Trying to overcome extra friction from additive depletion?



I think the manual also stated oil additives were a no-go.