Piston Slap on Cold Starts

[MolaKule]

Back in August we had a similar discussion.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=000331#000000

I still believe this offset wrist-pin design is the root cause of most piston slap problems.

In other words, it's a "designed-in" gremlin.

[ January 13, 2003, 12:54 PM: Message edited by: MolaKule ]

 

[jsharp]

quote:

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Originally posted by G-Man II:
Understanding the problem is the key to not worrying too much about it. The 3.1 and 3.4 actually have TWO clearance related noise problems: piston slap and wrist pins. It's never a good idea to push an engine hard when it's cold, and it's vitally important not to do that with these engines. But even in some 3.1s and 3.4s, the wrist pin and piston clearance problems can be so severe that the noise doesn't go away when the engine reaches operating temp. On conventional oil, mine still had a little "rattle" even when fully warmed up, but on Mobil 1 (and Shell Rotella T Syn), there is no discernable noise from either source except when it's first started in cold weather.

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That was what I was getting at and it makes sense to me. I've had a lot of Japanese vehicles over the years and they typically use overhead cams and solid valve lifters. They always have some top end rattle when they're cold ( the newer stuff is quieter ) until the clearances straighten out. No durability problems with those engines...

[ January 13, 2003, 12:52 PM: Message edited by: jsharp ]

 

[Drew99GT]

Mobil 1 must be too thin for "piston slappers". My car sounds terrible with mobil 1, and most others on this board say the same. Regular old penzoil really has made my car quieter, so the moly in there must cushion the piston skirt a bit? Who knows, but if it's 3 bucks less a quart than the mobil 1 and seems to run better and quieter, it's a winner in my book

 

[L8274]

quote:

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Originally posted by G-Man II:

quote:

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Originally posted by seldont:
Guess I may try the Pennzoil. Been using the 5w30 Motorcraft. Does the Pennzoil have particular advantages?? I have 6 qts on the shelf. Got it at Wallyworld on sale recently.

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Actually, Pennzoil and Conoco (the makers of Motorcraft oil) share common base oils. Their base oils are produced by their joint venture, Excel Paralubes, though this is soon to change now that Shell has bought out Pennzoil.

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As in Pennzoil will no longer use that base oil produced from the plant unless it is purchased from Conoco and whoever purchases the other 1/2 interest in the plant by October of 2003.

Does Shell produce a group II base oil or purchase it from other companies ? Is it true Castrol buys it's base oils from Shell? Or does Castrol buy from the less expensive choices at the time they need more base oil ?

 

[Ken2]

Castrol is owned by BP. Does it matter where they get their base oil, as long as it meets their specs? We see the real-world results in used oil analyses.


Ken