sprucegoose Posted December 17, 2018 Report Share Posted December 17, 2018 So Ive owned this 09 with the 3.6L DI motor for a couple months now... Quite happy with it, very quick and comfortable! The question keeps popping in my mind though when i tank up... Shouldnt i be getting close to the 27mpg on the sticker for highway? Best ive ever seen is 22... Could it be aging AWD drivetrain dragging this down somewhat? 104K mi now... New plugs and air filter. I drive fairly moderate for the most part, almost all highway. Usually average mph for tank is around 50Mph. Also, oil pressure is around 25-30psi at idle when warm. Is this normal? Seems a litle low to me... Would like to see 40 or so. '09 Cadillac CTS-4 3.6 direct injection, 128 K mi. '15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi '70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration! Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted December 17, 2018 Report Share Posted December 17, 2018 I believe the 3.6 AWD was rated for 25 mpg highway although the EPA site shows it both ways. https://www.fueleconomy.gov/feg/bymodel/2009_Cadillac_CTS.shtml The MPG is most effected by your driving style, then by things like a tire air pressure, clean air filter, clean oil. I am not sure on the oil pressure. Oil pressure is at best an indirect indicator in my book, as long as it is not zero. 25-30 psi at idles sounds fine. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
cdgrinci Posted December 17, 2018 Report Share Posted December 17, 2018 At idle, 25 to 30 psi sounds okay (especially when warm); this can also be affected by viscosity of the oil you are using. And your hwy mileage is going to be determined by speed , wind direction as well as engine health. Try setting your cruise control to 60, on a flat section of road and put your mpg on instant and see what you get. At 50 mph, yes, you should be doing better than 22. Is your transmission going into torque converter lock-up; this makes a pretty big difference too. Chuck '19 CT6, '04 Bravada........but still lusting for that '69 Z-28 Link to comment Share on other sites More sharing options...
sprucegoose Posted December 18, 2018 Author Report Share Posted December 18, 2018 All good points, which ive already considered most of them... The oil pressure just makes me nervous after my last 5.3l started taking a dive with a bad oil pump seal. I was talking 50mph AVERAGE when i was talking about gas mileage. Yes, ive done the 60mph test and it usually will get about 23-24 mpg on the flat for a while. Yes, this 6spd trans is going into TC lockup, unlike my previous Northstar... Im just surprised because i was getting better mileage with my 03 SLS with V8, much bigger heavier car also. I averaged about 24-25 on my commute with Betty White. I drive her a bit harder also, blowing out the carbon daily! 😜 '09 Cadillac CTS-4 3.6 direct injection, 128 K mi. '15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi '70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration! Link to comment Share on other sites More sharing options...
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