Patman : Rotella T 5w-40 ?

[Drew99GT]

http://www.rotella.com/products.php

Scroll down and you have the link to the Rotella data sheets. It's pretty thick stuff! I noticed that when installing it.

 

[DJ]

Not a 3.8 but this stuff quieted down my roller rockers quite a bit, even with a larger than stock cam and stiff springs to match. It is quieter than it was with Amsoil 10W30, and much quieter than any 5W30 I had used.

 

[bob555]

I like the Rotella 5W40 for applications that require a thicker oil, high mileage cars, budget concerns, etc. But, on the 3800 in question, it doesn't sound like any of those really apply. So, I would just use the M1 10W30, possibly extend the drain a little to save the difference between $4/qt M1 and $3/qt rotella.


Once M1 5W40 hits my area (Lansing, MI), I probably will see less and less applications for Rotella! Espicialy if I can buy Delvac 1, err Truck and SUV for Wal-Mart prices!

 

[haley10]

quote:

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Originally posted by bob555:
I like the Rotella 5W40 for applications that require a thicker oil, high mileage cars, budget concerns, etc. But, on the 3800 in question, it doesn't sound like any of those really apply. So, I would just use the M1 10W30, possibly extend the drain a little to save the difference between $4/qt M1 and $3/qt rotella.


Once M1 5W40 hits my area (Lansing, MI), I probably will see less and less applications for Rotella! Espicialy if I can buy Delvac 1, err Truck and SUV for Wal-Mart prices!

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Good points.

 

[Forkman]

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Never heard any piston slap out of a 3800.

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Me either. I don't know exactly what the ticking was in the Regal. I was referring to the piston slap in the 3.1L and 3.4L suspected to be inherent with the short piston skirt design GM chose.

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There was no noise like you describe with any of these. All were 10W-30.

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I haven't had any noise with anything but the M1 10w30. I even tried mixing in a bit of M1 0w40. That lessened the noise, but not as much as switching to another brand besides M1.

Prior to the M1, the cars first 8mo. of ownership with us was on Valvoline dino. Once again, no noticeable ticking with it either.

I don't know. This particular engine just doesn't seem to like Mobil1.

 

[blsnelling]

quote:

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Originally posted by KW:

quote:

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Originally posted by blsnelling:
Is this Rotella Synthetic friction modified?

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Nope not at all. It's just good ol group III oil. I really like the stuff.

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Since this stuff isn't friction modified, what does that mean in a gasoline engine. Wouldn't a friction modified oil be better? Is the new Amsoil or Mobil 5w-40 friction modified? What exactly do we mean by "friction modified"?

 

[T-Keith]

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Originally posted by Forkman:

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Never heard any piston slap out of a 3800.

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Me either. I don't know exactly what the ticking was in the Regal. I was referring to the piston slap in the 3.1L and 3.4L suspected to be inherent with the short piston skirt design GM chose.

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Then perhaps it's not the piston design that is the problem.

Not all 3.1s and 3.4s have the problem either. My sister's 3.1 runs great, never heard a peep from it.

-T

 

[haley10]

I think GM screwed up on some of these. I think I remember a TSB on under-sized pistons, being replaced if the customer complained enough. I'm pretty sure it was on the 3.1 where incorrect pistons were fitted.

 

[Forkman]

The 3.1L, 3.4L and one of the new "inline" truck engines they recently introduced. On some vehicles the pistons fitted are slightly out of spec (just barely too small). The short skirt allows the piston too much lateral movement that would be prevented by a longer skirt design. The piston thus "slaps" the wall of the cylinder. The fix was to replace the number 5 and 6 pistons on the 3.xL engines with pistons that had ceramic coated skirts. This fixes most of the slappy engines.

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My sister's 3.1 runs great, never heard a peep from it.

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"In the case of the famous GM piston slap engine defect, the piston design with hypereutic (high silicon content aluminum alloy) pistons, reduced or eliminated piston skirts (to reduce reciprocating mass), and a higher ring pack to reduce unburned fuel mixture on the sides of the piston crown have made piston to cylinder bore fit much more critical. The amount of tolerance (variation or margin) in allowable clearance between the piston and cylinder bore to prevent audible piston slap has been reduced by a factor of at least 50%. Consistently hitting the narrower margin for piston to cylinder bore tolerance has not happened for GM during mass production. Thus, some engines have no audible piston slap and some have piston slap on only one or two cylinders."

 

[T-Keith]

Yes, so it's not just the short skirt that causes the problem, it's the combination of a short skirt, high ring set, and out of tolerance piston dia. BTW, 3.8's have a moly coating on the piston skirt, not sure about the 60s(3.1, 3.4).

Another thing of interest. There are aftermarket companies making forged pistons for the 3.8. As you may or may not know forged pistons expand more than hypereutic. In some, but all cases, people have reported cold start piston slap.

Remember almost all engines made today have short skirt pistons, or soon will. It's an inevetable change, that started many years ago, when car companies started making their V8s more compact. Most notched the pistons for counterweight clearance. If you really want a long skirt, try a Buick Nailhead, they notched the counterweights instead, so they have a very long piston skirt.

-T