Today it was time to get my 2011 CTS4 it's oil change as my in car oil meter read 0%. Going into this oil change my PSI guage would hover just on the left side of 25 when fully warmed up. Now after a complete oil change I see it hovering on the right side of 25 when fully warmed up. Is this normal to see a slight increase on your PSI guage with new oil.
New oil vs old oil
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In case he doesn't respond: I changed my oil on Friday. OLM was at 7%. I did just over 8200 miles, last changed in Aug 18. Pennzoil Ultra Syn, topped up twice during that stretch (each time waited until down two notch, checked often).
I hope the OP is checking that level often.
I hope the OP is checking that level often.
I'm sure he is.
Thanks for the info, Jay--this is my first time servicing my CTS based on miles, not time.
Seems on par with where I'm at now. Currently at ~50% on the OLM after ~4k miles.
I usually service around the 10% mark and get around 9000 mi. on my 3.8 V6 & 6500 mi. on my 5.3 V8.
About 6000 miles. I had the last oil change done last August. Most of my driving during the past 6 months has been city driving at about 75-80%. I bought the car last Feb and in 12 months have had two oil changes. Over the last interval from August to now I also had to replace about a quart of oil over that 6000 miles. I only use synthetic, and both oil changes have been done at the local Cadillac dealership.
Three things come to mind.
Oil tends to shear down in viscosity over time.
Fuel dilution, which is more prevalent with city driving, will lower the viscosity of oil.
Perhaps the dealer put in a slightly thicker grade or changed suppliers resulting in a slightly thicker oil.
With only a slight difference in oil pressure I wouldn't worry about it.
Oil tends to shear down in viscosity over time.
Fuel dilution, which is more prevalent with city driving, will lower the viscosity of oil.
Perhaps the dealer put in a slightly thicker grade or changed suppliers resulting in a slightly thicker oil.
With only a slight difference in oil pressure I wouldn't worry about it.
Yes the long chain polymers become short chain.
Oils have improved steadily over the years.
Usually when I see a drop (about 3,000 miles) I change the oil. From a bit under 25 to a bit over at hot idle is about that.
I always use synthetic oil (usually Mobil 1) and change the filter (not Fram) every time. Just changed mine and it took about 45 minutes in my driveway mainly because I am slow and had to R&R the belly pan.
Oils have improved steadily over the years.
Usually when I see a drop (about 3,000 miles) I change the oil. From a bit under 25 to a bit over at hot idle is about that.
I always use synthetic oil (usually Mobil 1) and change the filter (not Fram) every time. Just changed mine and it took about 45 minutes in my driveway mainly because I am slow and had to R&R the belly pan.
2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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For Long:
Oil change miles vs % reading
The dealer changed the oil when I bought car at 52,000 miles on 5/2017 and I have used Mobil 1 5W-30 since.
Miles on oil % reading date
5960 29% 8/25/17
7990 19% 12/29/17
8040 15% 5/5/18
8862 9% 9/22/18
1000 ? 10/8/18 dealer did rear main oil seal.
Oil change miles vs % reading
The dealer changed the oil when I bought car at 52,000 miles on 5/2017 and I have used Mobil 1 5W-30 since.
Miles on oil % reading date
5960 29% 8/25/17
7990 19% 12/29/17
8040 15% 5/5/18
8862 9% 9/22/18
1000 ? 10/8/18 dealer did rear main oil seal.
Hey Flash, do you know if your CTS has had the oil change interval reprogramming performed? Mine has and is now reading 35% oil life at ~4000 miles and historically has had the oil changed every ~5000 miles. I don't know what motivated the previous owners to change at ~5k consistently but at the rate I'm going the oil life will be below 20% at 5000 miles. It dropped from 50% to 35% in the last ~750 miles. I know that there are numerous variables affecting the ECU's oil life estimate but I also know that the OCI was cut dramatically with the timing chain related oil life reprogram.
Oil filters can affect pressure also.
2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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2,925 Posts
CaddyFred, OIC reprogramming ? I do not know, but car had all the recalls when I bought it and I have had it to the caddy dealer 5 times since last June and they would have done any updates if needed.
Yes, it has the latest ECM calibration file for engine operation.
I asked because I saw significant variance in owner reported oil life percentages and wonder if this is related to ECM programming. There are actually 4 different ECM calibration files that change the oil life monitoring program. I have verified that I have the latest.
Part Number CVN Description
12645975 C1FDF065 New calibration to enhance the operation of the engine oil life monitor to more accurately identify the required oil change interval.
12644358 CC483102 New calibration to enhance the operation of the engine oil life monitor to more accurately identify the required oil change interval.
12641240 0692B27B New calibration to address oil life monitor accuracy.
12632821 5011A7EA New calibration to correct rough idle after a cold start
12628389 C655D45C New calibration for start of production
12627276 C923A3E9 Engine Operation
If anyone would like to check, just enter yout VIN here: https://tis2web.service.gm.com/tis2web/
1) enter VIN
2) Click on 'get cal id'
3) select 'ECM' click 'next'
4) select module 'engine operation'
The cal file programmed to your ECM will be indicated. Mine is the latest, 12645975
I have no idea exactly what was changed in the various cal files but it is known that the oil change interval (OCI) was shortened.
2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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2,925 Posts
It seems I have a more resent one than yours.
Mine is 12646454 New calibration to enhance the operation of the engine oil life monitor to more accurately identify the required oil change interval.
Mine is 12646454 New calibration to enhance the operation of the engine oil life monitor to more accurately identify the required oil change interval.
Your cal file isn't applicable to my '09, only the ones listed in my previous post. The important thing is that you have the latest file for your car.
It appears that the difference between our oil life measurements are due to other factors. IIRC 2010+ came with a revised timing chain and possibly numerous other small changes to both hardware and software.
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