GM 3.1 new coated pistons & Mobil 1?

[DoctorZ]

I have a 2001 Buick Century with a 3.1 V-6. It _had_ the classic GM 3.1 piston slap problem. I have a really great local Buick dealer and they replaced all 6 pistons (at 17,000 mi) with the new pistons with teflon pads on the skirts. No more piston slap! Smooth and quiet. I looked at the old pistons, and a couple of them (#1 & #3?)had teflon pads on the skirts, BUT the teflon was worn off. I think this is what caused the piston slap. SO, my question is: Since the Penzoil 5W-30 dino I was using didn't seem to keep the teflon pads from wearing on the old pistons, would Mobil 1 5W-30 provide any better wear protection for the teflon pads on the six new pistons? My thinking being the synthetic will adhere better while stopped and provide quicker lubrication on startup. Apparently, once the teflon wears off, the piston slap starts. So my goal is to keep the teflon pads from wearing. Thoughts? DoctorZ

 

[Ken2]

If it is indeed a PTFE (Teflon®) coating, here's more info: http://www.hpcoatings.com/engine_coatings.htm I don't know what oil might help, except maybe one with a big slug of moly. Ken

 

[G-MAN]

Based on what that web page is saying, the coating probably isn't PTFE. It's a form of moly called Molykote developed by DOW. PTFE SHED'S oil, which winds up INCREASING wear. The moly coating ATTRACTS oil. However, if the scuff coating on some of his old pistons was worn off, maybe that's an indication that the coating was PTFE. Hmmmm.... NB: Molykote is used on the piston skirts of the 3.5 liter engine in my 300M. [ May 07, 2003, 01:10 AM: Message edited by: G-Man II ]

 

[Michael SR]

do you have pictures of the old pistons? fwiw, if it's a solid film lubricant as with most other pistons i've seen, the coating does indeed wear off. -michael

 

[Al]

Maybe they should try the Molykote on their leaking intake manifold gaskets.This gasket is garanteed to fail during the service life of the engine to the tune of $500 [ May 07, 2003, 08:26 AM: Message edited by: Al ]

 

[DoctorZ]

quote:

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Originally posted by Michael SR: do you have pictures of the old pistons? fwiw, if it's a solid film lubricant as with most other pistons i've seen, the coating does indeed wear off. -michael

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Unfortunately, no. The dealer had to send them in for warranty reimbursment. I only got to look at the box of pistons when I picked up the car after warranty repair (and I don't have a digital camera, yet). However, the square pads on the skirts of the two old pistons was worn in an inverted "U" shape, with the coating completely gone along the bottom and in the center of the pads. DoctorZ

 

[Drew99GT]

Based upon my 3.4L experiance with mobil 1 and many others on this board, I'd steer clear of mobil 1. Honeslty, that skirt coating will wear off with any oil you use and many engines with the coating still in tact, slap like crazy. If you wanted to use the best oil for piston slappers per everyone elses findings here, redline is perhaps your best bet.

 

[JohnBrowning]

The pistons slap because of poor design. The elimantated most of the skirt to rudce friction and weight and they moved the rings up close to crown for better ring sealing when cold. Both of these things are really bad to do to a piston if long service life and good oil control are wanted. Oh did I mention that piston slap is guranteed with this design. Alot of companys are doing it as a cheap way to improve cold vechile tailpipe emission especial on snap test! lets all thank California for manateing crappy cars for use! THe good news is if you rebuild it your self with TRW pistons TRW has destroked them a bit to move the the piston rings away from the top giveing better service life. They also increase the skirt area. Dodge has recently done this as well with their new engine designs. This is the main reson the Northstar engines are none oil burners. The Northstar engine series was the first widespread use of this piston design.

 

[G-MAN]

Well, unlike Drew, Mobil 1 does a good job of getting rid of the piston slap in my 3.4, and the 0w40 seems to be the best at it. Now that the weather has warmed up, I have almost NO piston slap at cold start (so long as the temp is above 50F), and once the engine reaches operating temp, it's gone completely. (My van has almost 150,000 miles on it, BTW.)

 

[Drew99GT]

I must have ended up with a lemon! I never went over 2,000 rpm for the first 3,000 miles, changed the oil twice within the first 3,000 miles etc. I did however, race the crap out of my Grand Am, but that was with about 2,500 mile mobil 1 oil changes Yea, I didn't know better back then. But by 60K, she was way way down on power and running like a tractor even with a FULL tune up.

 

[JohnBrowning]

In my post the word none should read known. Sorry for all the typo's!

 

[jc1990]

that 3.1 engine is a pos anyway i have a 94 sunbird and 97 grandam with these motors they both suck take my advise stay far away from pontiac

 

[Patman]

quote:

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Originally posted by jc1990: that 3.1 engine is a pos anyway i have a 94 sunbird and 97 grandam with these motors they both suck take my advise stay far away from pontiac

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Next door to me is a guy with a 1990 or 91 3.1L Sunbird with 380,000km on it and still going strong. I hear that thing start up every morning and it still sounds healthy, no piston slap either.

 

[DoctorZ]

quote:

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Originally posted by DoctorZ: I have a 2001 Buick Century with a 3.1 V-6. It _had_ the classic GM 3.1 piston slap problem. I have a really great local Buick dealer and they replaced all 6 pistons (at 17,000 mi) with the new pistons with teflon pads on the skirts. No more piston slap! Smooth and quiet. I looked at the old pistons, and a couple of them (#1 & #3?)had teflon pads on the skirts, BUT the teflon was worn off. I think this is what caused the piston slap. SO, my question is: Since the Penzoil 5W-30 dino I was using didn't seem to keep the teflon pads from wearing on the old pistons, would Mobil 1 5W-30 provide any better wear protection for the teflon pads on the six new pistons? My thinking being the synthetic will adhere better while stopped and provide quicker lubrication on startup. Apparently, once the teflon wears off, the piston slap starts. So my goal is to keep the teflon pads from wearing. Thoughts? DoctorZ

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Well, I'm going with Mobil 1 5W-30 and Wix filter. We'll see how the new pistons (with the anti-wear pads on the skirts) hold up... DoctorZ