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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #81
Sorry for the long absence, I got stuck on a timing chains and tensioners changeout, on an 08 Suzuki XL7 AWD. Finish tomo, finally. Only took 3 days, but cost me another 2, because my helper left the ground wire off that he removed(I never knew it was there(honest Lol), and was throwing 2 4 6 injector codes. Finally found it when I was starting to tear it back down!
Anyway, reversing PVC flow didn't help. Only got 250 miles til down a half qt. again. I'm gonna pull the end of the pcv valve out, and secure some kind of filter on it, and the other end too, to see just how much oil is going thru the pcv, and how much is from the rings. Im not done yet with this problem. I might tie the end of the dirty line inside a clear container, to see if, or how much blowby is going on. I have a one way 3/8" to put in the fresh air side, to keep it out of the intake(airbox). More later!
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #82
Well guys, this is a funny car. Since I disconnected the manifold vacuum from the pcv system, it has used a half qt. in only 200 miles. I'm gonna leave it down, to see if it slows down any. I was driving the car a little harder, but not "hot rodding" it. So, it seems to be a combination of oil being g sucked thru the pcv system AND getting past the rings. Probably mostly when off the throttle, because this setup has a tremendous vacuum pull when idling, and when going down the hills around here, unlike other cars, the throttle plate is closed(pulling vacuum)m especially in sport mode, which I like! That's what gives you the feel of a standard(clutch) transmission. The very first thing I did the pcv extension helped greatly. It stopped the 0420(?) cat codes, and misfires, smoothed out the idle, upped mileage, and gave an overall performance gain. Was like a different car. But after that, I cant seem to get much more improvement on the oil consumption. I tried. 150,000 miles, and the rings leaking. I hate to put a heavier oil in it. (10-30) But I might try that. I'm gonna run a qt of Rislone through it first, doing some low gear, high speed downhills, maybe if the rings are gunked, I can free em up. We'll see. More later.
 

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Registered
2007 CTS 3.6 >120k miles
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427 Posts
I agree that the overall problem is likely more than a single issue, but the pcv system appears to be the biggest contributor. Rislone or another cleaner is a good idea to make sure things are clean, but I don't think going to 10w30 is a good idea. I switched to Pennzoil Platinum HM 5w30 for about a year and oil consumption disappeared. However, I then started to hear my timing chain at startup so I switched to PPHM 10w30. This made it worse so i switched back to 5w30 and it got better. After replacing the chains I used 5w30 Magnatec and only noticed the consumption on extended freeway runs. I recently switched to Valvoline synthetic HM 5w30 at my last oil change and will see what happens.

If I were to switch to a thicker oil I would probably try 0w40 or 5w40. The rationale is that the oil would be thin enough at startup to protect the chains but would be thick enough to handle the higher rpm of freeway driving. Has anyone on the forum tried this? If it doesn't work I will just stay within 5w30.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #84
You're right,I forgot about the 0 weight oil's, and yea, I was going the wrong way with weight. I'm a big fan of Valvoline HM. I use the synthetic blend 10-30 in my 95 Eldo and it stopped using. Has 245,000 on it now. I gave it to my girlfriends son the other day. I dont think they make a 5-40 synthetic? Or do they? If so, I would start adding that each time it's down, and see if it made any difference. Maybe make my own blend, a 7.5-35, out of 5-30 and 10-40!
 

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Registered
2007 CTS 3.6 >120k miles
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427 Posts
Valvoline has 0w40 and 5w40 syn MST oil (for euro cars), as does Pennzoil. Delo or other 0w or 5w40 synthetic HD oil would probably work, too.

I still dont know whether the thicker will help or would just be another failed effort! For now I am just cautiously hopeful that the Valvoline synthetic HM will help...
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
·
166 Posts
Discussion Starter #86
Valvoline has 0w40 and 5w40 syn MST oil (for euro cars), as does Pennzoil. Delo or other 0w or 5w40 synthetic HD oil would probably work, too.

I still dont know whether the thicker will help or would just be another failed effort! For now I am just cautiously hopeful that the Valvoline synthetic HM will help...
I've been using the the Valvoline hm since I got the car, no difference yet. I started with the Mobil 1, then been adding the Vhm. Gone thru bout 2 changes, so far.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #87
I'm gonna look for the 5-40 Vhm, or next best next time I'm at Walmart. Gonna start adding that and see what happens. Am thinking about getting another ly7 from U-Pull, and putting a rings n bearing kit in it, in my spare time. Oh! Wait! What spare time!?
 

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Registered
2007 CTS 3.6 >120k miles
Joined
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427 Posts
I'm gonna look for the 5-40 Vhm, or next best next time I'm at Walmart. Gonna start adding that and see what happens. Am thinking about getting another ly7 from U-Pull, and putting a rings n bearing kit in it, in my spare time. Oh! Wait! What spare time!?
The valvoline site doesn't show 5w40 HM, just the MST. I haven't seen the MST on WM, AAP, or AZ shelves so may need to order elsewhere. My local WM has Pennzoil euro 5w40 which is probably similar.
 

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19 Posts
I'm gonna look for the 5-40 Vhm, or next best next time I'm at Walmart. Gonna start adding that and see what happens. Am thinking about getting another ly7 from U-Pull, and putting a rings n bearing kit in it, in my spare time. Oh! Wait! What spare time!?
Thanks for your detailed posts. I wondered if you'd made any progress with the oil issue?
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #90
I have, I drive it every day 50+ mile round trip, and since I've been pouring in the Valvoline 10/40 High Mileage blend and driving it harder(letting it wind out some), the Cat codes have stayed off, and mileage is slightly better.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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166 Posts
Discussion Starter #91
I still have to add 1/2 qt oil every few days, but it's running better without the vacuum lines hooked up to the intake.
 
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