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2005 Deville
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16 Posts
Discussion Starter #21
The engine runs, the torque converter spins, the transmission scavenge and pressure pumps operate. Almost all the fluid in the pan is pumped up into the side tank - which is where the dipstick is. So, with the engine running in P on a level surface you measure fluid level. The "no fluid on the dipstick with the engine off" is a caution against overfilling.

There is no need to disconnect the top radiator hose to get to the transmission dipstick.

Your engine should easily get 2,000 - 4,000 miles to a quart of 5W-30 oil. Mine gets over 6,000. You probably need to aggressively exercise the engine out in the boondocks.

Study this - all of it. Written by a CF member who was a GM Northstar Systems powertrain engineer. It was written before the 2000 changeover to roller cams, so some of it is obsolete, as is the section on the discontinued use of cooling system sealant tablets. Read the WOT section - "Occasional full throttle operation is good ..."


This is a Seville engine compartment, the air intake system and surge tank is a bit different, but the parts ID is the same as your Deville. Which model - base, DHS, DTS ? It makes a difference in advice. You NEED to subscribe the car to the online GM/Cadillac service manuals - www.alldatadiy.com

View attachment 575011
My mechanic recommended I use 10w -30 since the car has high lot of miles because in short it’s thicker & for such for such a trip
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,220 Posts
NO !!! That is a very incorrect statement. Our engines use a good 5W-30 engine oil - that began in 2000 when the engines went to roller cams.

A correctly maintained late Northstar is not even broken in at 100,000 miles. Ask your mechanic if he has ever replaced a Northstar water pump drive tensioner pulley - and why - and when. You're overdue.

Regardless, the length of the trip has exactly nothing to do with engine oil "thickness". 5W-30 or 10W-30 are exactly the same viscosity when warmed up and on the road. 5W- just flows better for cold startups. No other reason.

Here's your valvetrain and one of the reasons the car has a better EPA fuel mileage rating than the pre-2000s.

2000+ roller valve actuator.jpg
 

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2005 Deville
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16 Posts
Discussion Starter #23
OK - that "hose" you're worried about is the intake hose for the AIR blower. Simply unclip the clamp and move it out of the way. Yes, when you twist/pull the black cap you'll see the dipstick feature.

You're wasting time and money with that cutesy K&N filter. Any oil carryover ant that $135 MAF is toast.

The second picture - the airbox is retained by a machune screw or two and that rubber-lined brace is one of the mounting studs - just slides out when the main retainers are removed. Did you say Torx screws?

You really need the GM service manuals for reference - you're now flying blind with a car that bears NO resemblance to what you may be familiar with.

GM service manuals - Chilton and Haynes are far, far too generic to be of any help.

Please stop shotgunning out posts 1 minute apart - wait for info to come, study a bit, them make a summary post/question. Thanks.
Ok I will wait a few minutes before posting etc. I am using the original 2005 Cadillac book that came with the car also can the intake hose be detached while the car is running as the manual and a few of you guys insisted to check the transmission fluid? And yes I may have said torq screw I meant wrench
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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If you remove the intake duct at the filter box and leave the MAF connected and in line the engine will run just fine.

I don't believe there are any specific torque settings for the air filter box.

FWIW, my 2002 does 2 yearly runs from MD to FL and back - 1660 miles round trip, on 5W-30 synthetic oil, uses not one drop, and has done so since 2002. What does your oil fill cap recommend for engine oil ? (Note that Ford cars and light trucks use 5W-20 engine oil.) As some newer GM cars now do.
 

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2005 Deville
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16 Posts
If you remove the intake duct at the filter box and leave the MAF connected and in line the engine will run just fine.

I don't believe there are any specific torque settings for the air filter box.

FWIW, my 2002 does 2 yearly runs from MD to FL and back - 1660 miles round trip, on 5W-30 synthetic oil, uses not one drop, and has done so since 2002. What does your oil fill cap recommend for engine oil ? (Note that Ford cars and light trucks use 5W-20 engine oil.) As some newer GM cars now do.
5w-30 so from here out I’ll put that in he’s a good mechanic very good like I said I told y’all his excuse for such also the k&n filter was his idea said the engine can breath or sum like that

Update for everyone that has chipped in.....I finally checked the transmission dip stick and it was very low it is now up in the cross hatches I will year drive it and give feedback that way anyone in the future having the same problem can get help through the forum thanks guys 🙏🏽

Update for everyone that has chipped in.....I finally checked the transmission dip stick and it was very low it is now up in the cross hatches I will year drive it and give feedback that way anyone in the future having the same problem can get help through the forum thanks guys 🙏🏽
The car drives fine the hard shifting has stopped thanks for everyone’s input!!!
 

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White Diamond '03 DHS (with DTS floor shift)
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86,319 Posts
For what it's worth, I have used 10W30 in my '03 since 17k when I bought it. It now has 126K.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Sure it will. The 5W-30 was phased in after the change to roller cams - and because the bean counters figured it would lower cold engine oil drag, resulting in a microscopic fuel savings - which could be calculated into the EPA-mandated CAFE figures.

I'm going by which oil is recommended by Cadillac in your owner's manual and on the oil fill cap. You use what you want.

Do you use regular 87 or premium 91/93 gasoline? Your engine is calibrated to run and make full rated power on regular - but, as with engine oil, run what you want to.
 

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2005 Deville
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16 Posts
Discussion Starter #30
Sure it will. The 5W-30 was phased in after the change to roller cams - and because the bean counters figured it would lower cold engine oil drag, resulting in a microscopic fuel savings - which could be calculated into the EPA-mandated CAFE figures.

I'm going by which oil is recommended by Cadillac in your owner's manual and on the oil fill cap. You use what you want.

Do you use regular 87 or premium 91/93 gasoline? Your engine is calibrated to run and make full rated power on regular - but, as with engine oil, run what you want to.
Who’s whoa whoa!! I was told by a Cadillac rep the 2005 Deville takes 93....so that’s what I use I’m going to check my manual see what’s recommended. I’d save money using 87 if so. Also I agree I ultimately think it’s best to use what is recommended regarding oil the 5w30
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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When Seville died in December 2003 and Deville died at the end of the 2005 MY (June 2005) the Northstar engines were redesigned and recalibrated for the newer Cadillac vehicle models. Some of those later models require 91/93 premium; some are set to run on 87. It's in the book.

There are quite a few very different Northstar powertrains - every one has the necessary operation and service info in the owner's manual.

Your owner's manual (Fueling, Gasoline Octane) may say something like "Use a gasoline of at least 87 octane but, if the car is used for trailer towing, mountainous driving or race purposes, a premium fuel should be used or blah, blah, blah ..........".
 

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2005 Deville
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16 Posts
Discussion Starter #32
When Seville died in December 2003 and Deville died at the end of the 2005 MY (June 2005) the Northstar engines were redesigned and recalibrated for the newer Cadillac vehicle models. Some of those later models require 91/93 premium; some are set to run on 87. It's in the book.

There are quite a few very different Northstar powertrains - every one has the necessary operation and service info in the owner's manual.

Your owner's manual (Fueling, Gasoline Octane) may say something like "Use a gasoline of at least 87 octane but, if the car is used for trailer towing, mountainous driving or race purposes, a premium fuel should be used or blah, blah, blah ..........".
575046
 

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I bought a 2005 Cadillac Deville about 3 weeks ago with123,000 miles allegedly traded in by an older granny owner. The car looks well inside and out and drived well I had a very trusted mechanic look over the car for days & do some work on the car for much cheaper than a shop. I took a trip to Memphis from Orlando the car had no issues what so ever during the trip. As day after the trip my check oil level came on my oil was extremely low by the time it ended (no oil on the dipstick). I was recommended to add 1 then 2 more (totalling 3) quarts of oil the warming went away the stick had a bit more oil on it. Car drove fine the whole day until night after getting off a short highway it started hard jerking when I switched gears I now have it parked at a Walgreens and am not going to drive it any help is appreciated
I have a 2008 DTS, with 196k mikes and had a 2002 DTS. After 100k miles or 10 years, you get the Northstar leak. The 2 piece engine block leaks. It gets worse with time and you have to take the entire engine apart to replace the seal. You may also have a valve cover leaking. I replaced my seals on the covers about 150k Miles. Filling the engine oil up to the top of the dipstick will cause about 1-2 quarts leak loss, due to the Northstar leak alone. But you said you have no grimy undercarriage? I also suspect the car sat a long time and seals dried out for lack of use. Sometime running will replenish seals a little bit. But it won’t fix it. How was your coolant level and what color does the fluid look like?
 
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