Cadillac Owners Forum banner

Speaking of Oil Pressure Gauge

9K views 7 replies 4 participants last post by  jghiller 
#1 ·
After the recent post on a question about oil pressure readings I have been watching mine more closely and noticed a decided difference with my 2012 Coupe with the DI engine versus my prior 08 CTS with the 3.6L engine. Or perhaps there may be an issue.
I have noticed that before the engine reaches normal temp. reading, even now when its summer, that under normal acceleration the gauge goes up to just about 100psi and then settles down above 50psi while driving below 60mph. It will move up to about 75psi once I reach highway speeds. Once the temp gets to the normal reading just below 200 degrees, the oil pressure readings tend to come back down to around 50psi when driving constant speeds. Acceleration at that point doesnt peg out the oil pressure as it did when the engine was 'cold'. Have others seen this high pressure when first starting out in the 12 Coupe - routine acceleration, engine not yet at normal reading with oil pressure near 100psi? It makes me worry a bit if I happened to do a harder acceleration even though at summer temps the engine, though not at normal temps, isnt that 'cold'.
 
#2 ·
I see the same pressures and differences on my 09 DI and I've always accepted it as normal. Ambient summer temperatures still won't heat the oil high enough to eliminate the difference in pressures on a "cold" start. The oil is also a bit hotter than the coolant at operating temperature so it may take longer to see the pressure stabilize.

It's probably better to see a higher pressure at start-up to know that the pump is working well and its trying to force oil throughout the engine. Low pressure would be bad.
 
#3 ·
jurzdevil - thanks for the update that you are seeing the same jump after initial startup. I think I will most likely take things easy until she's warmed up completely. I would want to be on the safe side and not do any hard accelerations until I know more about the cars operation. Just bought it and only have 1K miles so far.
 
#4 · (Edited)
Of course.. oil generally thins when heated and thickens when cooled, therefore it's normal to see higher oil pressure on a cold start, even in summer and even with a multi-grade oil.

As jghiller mentions, his '12 CTS Coupe is equipped with the latest design LFX 3.6L DI engine, whereas his '08 CTS Sedan was equipped with the LY7 3.6L non-DI engine. There may be a fundamental difference between the two models of engine with respect to specific oil pressures developed at varying operating temperatures and engine rpm.

Another item to consider regarding any reported differences in the observed cold start oil pressure and transition to normal operating temperature oil pressures [on a 2012 CTS 3.6L versus a 2008 CTS 3.6L] may be the fact that GM switched from "Mobile 1" full synthetic oil (utilized on the '08-'10 CTS) to GM's "dexos1" synthetic blend beginning in m-y 2011. There may be viscosity index differences between the two oils that could influence, to a degree, oil pressure characteristics, particularly on the climb from cold start to normal operating engine temperatures.

As info.. below is a copy/paste of some info I found online today about GM's dexos1 oil:

Here’s what GM says about dexos1™:
All 2011 are required to have this lubrication installed or it could, and very well will, void warranty on related repairs. dexos1™ is a new and more stringent specification that exceeds GF-4/API SM and the new ILSAC GF-5/APISN-RC classification. dexos1™ is factory fill and service fill in all GM gasoline engine vehicles. dexos1™ supersedes the GM6094M, GM4718M and GMLL-A-025 specifications for 2010 and older GM vehicles and is now the only motor oil GM recommends for those vehicles.
GM’s brand of dexos1™ is a synthetic blend, not a full synthetic. It has improved viscometric properties, creating less friction in the engine which contributes to improved fuel economy. It resists aeration, which enables fuel-saving devices, such as Variable Valve Timing, to work optimally. It offers improved oxidation and deposit-forming tendencies allowing emission systems to operate longer and optimally, and resists degradation between oil changes, extending the time and mileage interval between oil changes.
 
#5 ·
Thanks RAB - just never saw pressures pegged at 100psi. As for the switch to dexos1 - after the initial switch, Mobil1 5W-30 was also certified so I wouldnt expect to stop using Mobil1. Your thoughts? I most likely will still be buying my own oil for dealers to use assuming they go by a lower percentage with the OLM than I tend to like in order to meet the requirements of the free service coverage. Too expensive to pay their prices for oil.
 
#6 · (Edited)
^ jghiller, regarding GM's switch to dexos1 in m-y 2011 and your intention to continue using (buying) Mobile1 for use in your new 2012 CTS Coupe.. basically what you're saying is - despite your oil changes being free at the dealer (i.e. Cadillac free scheduled maintenance) with their utilizing dexos1 oil, you'd rather pass on the no-charge dexos1 oil and purchase Mobile 1 for your engine, correct?
What oil is in your engine at the moment? The factory of course would have applied dexos1.
When I bring my '11 CTS4 Sedan in to the dealer for free scheduled service I just let them install dexos1 - I haven't thought about using (buying) Mobile 1.
 
#7 ·
Don't count on getting Dexos1 from the dealer. Last time I got the oil changed I saw a Valvoline sticker in the corner of my windshield, Valvoline does not comply with the Dexos1 spec even though they claim it is the same.
Next time I get it changed I am going to insist I see whaere they are pumping it from.
 
#8 ·
RAB - If given the choice of installing GMs dexos1 oil versus Mobil1, I would prefer Mobil1. My concern is when the dealer would do the oil change under the free service. I have heard things like 15% for the OLM. Thats too low for me. I always have changed my oil once it gets around 50% depending on the time frame since last change. The dealer I bought the car from said they do the free service at 7500 miles. That shoudnt be an issue for me but it all depends on the OLM number. And of course - no matter what oil is used, it needs to come from the container, not an overhead barrel. That happened to me one time when despite telling the service folks to use the oil I brought in the trunk, the service guy went and filled the car from the overhead oil container. I may be a little picky, but I definitely would not allow dexos1 or any synthetic coming from that source. After I noticed them using the overhead, they had to drain the oil and put the oil in that I bought. That was a dealer down south. It doesnt bother me to pay around $26 at Walmart and do the oil change under my direction rather than get it free but long after I think it should be changed. Thats just how I prefer things.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top