oil consumption experiment

[Spykem4e]

Hi guys,

I just want your opinion about oil consumption that I don't get with my car. I own a 2005 cadillac cts with right now 194500 kms with the 3.6l vvt non-di v6 with auto transmission. The car always used oil, 1.5 qt per oil change usually (40% oil life left on the DIC) for the first 100k kms. After that, i decided to give it a shot and wait until the DIC tells me to change the oil(0% oil life left) and I've posted some results of UOA on the forum with great results I guess. Next month, I'll post the next one.. anyway.. I know most of Cadillac consume or use oil but I just want to share with you at what mileage, quantity added, brand etc.

For your infos: usually, the car first starts at 6h30 in the morning doing 60% Highway/40% city or 50/50 maybe + traffic + 1 hour min per day of idling. Stop the car and start it 20 times a day and come back at night at 7h00 pm. I'm a sales manager and my car is my office.

Note: after adding oil in the engine, the dipstick always showed "full".

Pennzoil Platinum 5w30:
Km on the car:
2 May 2009: 166908 (oil change with PP 5w30 gm4718m spec)
11 May 2009: 168876 .75qt of make-up oil.
27 May 2009: 171264 .40qt of make-up oil
5 June 2009: 172742 .5qt added
19 June 2009: 175315 1qt added
July 8th 2009: 178850 1 qt added

Total oil added with PP 5w30: 3.65 qt for 12468 kms
calculation: 1qt per 3416 kms.
I was tired of toping-off so I did an oil change.
Oil change at 179376

Mobil 1 5w30 gmspec 4818m
Km on the car:

July 9th, 2009: 179376: oil change with M1
August 31st, 2009: 184595: .7qt added before trip
Sept 11th, 2009: 187560: .6qt added
Sept 29th, 2009: 189888: .4qt added
Oct 29th, 2009: 194183: .6qt added

Right now, the M1 is still in the engine and the DIC is showing 21% oil life left. I'll wait until the Change Oil Soon so do the oil change and I'll keep the UOA results on the forum. But for right now:

total of 14807 kms with a total of 2.3 qts of added oil.
Calculation:
1qt per 6438kms.

What I'm seeing with M1 is that when the oil is new, everything is working number one with no consumption but as soon as I pass the 3k miles, its getting older and the consumption increases a bit. Also, there's no relation with hours of highway driven miles versus city driving. It consumes or doesn't thats it.

I don't know what you guys think. If its not pertinent information, tell me and I'll erase the post.

 

[raffy]

Interesting experiment, thanks for posting the results! It appears for yout Caddy that M1 is the better oil from an oil consumption standpoint. Looking at the numbers, it roughly cuts your oil consumption in half. Not bad for just changing to a different oil (or did you do something else, like MMO soak or whatever?).

I'm wondering what's so different between M1 and PP that causes PP to have higher oil consumption. Does it have something to do with the additive packages?

 

[Spykem4e]

Raffy, I did not MMO or engine flush or Auto-Rx. I'm old school and adding stuff in the crank case is kinda giving me the creeps for right now. Its been one year now since I can trust the OLM hehe.

Keep in mind that every month, I usually do the exact same driving (highway/city/traffic/idle time etc).

Also, just before PP, I used m1 10w30 because the 5w30 was back order for weeks. I didn't post anything about the 10w30 M1 because it was using 1qt per 800 miles. Prior to the 10w30, the car always used M1 5w30 except for one time (6000kms on dino oil) because the dealer did a mistake by putting dino oil and called me 1 months 1/2 later to tell me the mistake they made. But that's about it.

 

[raffy]

Spykem4e, I just looked at your UOA and it looks like you're getting less wear with PP. I am not sure about the big difference in oil consumption there; maybe it has something to do with PP being a Group III oil and Mobil 1 being a Group IV. Still, if I were you I'd probably stick with the PP and a 7500 mile (12000 km) OCI as you have done, especially since you put a lot of miles on your car.

 

[Spykem4e]

Raffy, for the wear, you have to keep in mind that the oil interval was:

with PP: 12400 kms + 3.6 qts
with M1: 16100 kms + 2.5 qts

so I have 4000 km more on the UOA.

 

[mechtech2]

I had a BMW that would barely use oil until 2,000 miles were racked up on the oil - anybody's.
Then it started to use it pretty fast.
Somehow, this engine beat up the oil - maybe the cam chain or high heat hot spots, or blow by.