Oil Suggestion to Quiet Down My Prius

Pennzoil motor oil
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I bought an 05 Prius with 228k miles on it. I have some piston slap that I am trying to quiet. In the cabin when driving and the gas engine is running it very faintly sounds like I might have a small diesel under the hood
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When I test drove the car it was fully warmed up and I didnt happen to notice it much. The next morning when cold started it was very noisy for maybe 15 seconds and then quieted down considerably.

My second day of ownership I changed the oil to Pennzoil Platinum 5w30 with a Purolator Classic. In 2000 miles it does not seem to have burned a noticable amount of oil.

With the miles I dont think I want to drop to the 5w20 or 0w20. So I think I will stick with the 5w30 or maybe try AFE 0w30. For the next change I'm thinking I might try Pennzoil Conventional and see if that might help quiet it down some.

Any suggestions? Thank you.
 
Try an HDEO which include gas engine ratings like SOPUS Rotella T 15W40.

Piston slap is an out of tolerance cylinder(s). Not much you can do about it except live with it or complete overhaul.
 
Originally Posted By: jetmech1
Piston slap is an out of tolerance cylinder(s). Not much you can do about it except live with it or complete overhaul.


Not necessarily true. The GM 3100 V6 and the 5.3L Vortec V8 are a couple engines that come to mind that were actually designed with piston slap when the engine is cold. I think the idea behind it was low friction when cold (but some slapping, too), but a 'perfect' seal when at operating temp. The later 3100 motors actually had some sound deadening around/in the motor to muffle the noise.
 
Originally Posted By: jetmech1
Try an HDEO which include gas engine ratings like SOPUS Rotella T 15W40.

Agreed, with a high mileage engine and the warmer months coming up Rotella 15w40 would be fine, in the winter switch over to Rotella T5 10w30 semi-syn, both available at Walmart at reasonable prices.
 
Quote:
Not necessarily true. The GM 3100 V6 and the 5.3L Vortec V8 are a couple engines that come to mind that were actually designed with piston slap when the engine is cold.


I almost mentioned the 5.3 piston slap problem, but wasn't it found out to be that GM actually produced a bunch of these and were indeed out of tolerance in the early 2000's? I know there were a bunch of unhappy GM owners on this issue. I remember reading something in some car mags about it. Didn't really pay much attention as I am your basic Blue Oval type. Any GM die- hards got the skinny on this?

Not saying your wrong, but I can't hardly imagine an engine actually designed with a piston slap. If this was indeed their explanation, then it sounds like a corporate kool-aid to me to get out of a huge recall to correct poor QC. I thought low tension rings are used for reduced friction (along with roller valve trains etc).
 
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I'd give the Pennzoil conventional a try. The 4.0L I-6 in my Cherokee is known for piston slap and valvetrain noise. It is quite the noisy motor. I've found the high moly in Pennzoil Conventional has helped quiet it down more than other oils such as Rotella or Mobil 1.
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Try Pennzoil conventional sn/gf-5 loads of moly and very robust for a cheap(er) dino. Lots of quieter running engines with it too. Give it a whirl and see if it helps! Also spend the couple extra $ for purolator pureone, the Pennzoil conventional may clean some nasty stuff out of your engine too!
 
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The older 2g Prii do sometimes burn oil and piston slap as they age. That engine is the least of your concerns though.

At your mileage, you will be needing (if you have not already) replacement of the battery pack, transaxle and combination meter. There are rebuilt and used options for these parts that you should start researching so that you can be prepared when they fail. If you have not done the transaxle fluid, get 4 qt of ATF-WS from the dealer and do it now.

Also, watch out for the axle seal (left), engine water pump, inverter pump, wheel bearings and 12v battery.

These are good cars but do be aware of their weak spots so you are not caught by surprise.
 
The Critic knows about specific issues with the Prius. I drive a Civic Hybrid, so I can only talk about hybrid engines in general terms. Quest mentions checking the valve adjustment, which is also a good idea.

Without hearing your vehicle, it's hard for me to separate what are normal from abnormal sounds. Ask your dealer or other hybrid owners. Hybrid pistons often sound "slappy" and like mini-diesel engines. The pistons are designed to fit loosely in the cylinders when they are cold, so that they have room to expand under the extreme heat of lean burn mode. If a hybrid engine runs smoothly and quietly, something is wrong.
 
Since the noise goes away after 15 seconds you may need to use a thinner oil. I think some Kendall 5W20 that is slap full of moly and titanium will cure the noise. Since you have a hybrid that car may have 228K on it, but that engine has about 25% less miles since it cuts off when you stop and the electric motor is assisting it. I still use 5W20 in my Honda that has 220K miles.
 
Originally Posted By: Dakir
Try Pennzoil conventional sn/gf-5 loads of moly and very robust for a cheap(er) dino. Lots of quieter running engines with it too. Give it a whirl and see if it helps! Also spend the couple extra $ for purolator pureone, the Pennzoil conventional may clean some nasty stuff out of your engine too!


Agree, should give a try, I tried Mobil 1, Pennzoil Platinum, Castrol Syntech, I feel like my engine is more smooth and quiet with Pennzoil conventional,and suprise, its dyno
 
Thanks for all the feeback.

From my experience it it defenitely not a noisy valvetrain. The valves are noisy at initial startup but they quiet down considerably.

I agree there is nothing that can be done and honestly Im not too terrbily concerned about it other than I would like to try to see if I can quiet it down a bit. And I was wondering if being setup a little "loose" was normal for a hybrid. It seems that may be part if it.

Before going to a higher vis oil, which I may eventually do, I would like to try a couple lower vis oils first. I run High Mileage Pennzoil in my van with 220k on it and it has really cut oil consumption but I have never thought of a High Mileage oil making an engine quieter. Is that a general characteristic of a High Mileage oil?

The service history is impeciable on the car. It probably the only reason I purchased it with the miles. At this point Im not the least bit worried about the HV battery pack. I have come across two individuals with over 300k on their original. The wheel bearings were already replaced at some point in its life, I dont remember the miles, as well as the water pump and inverter pump. Perhaps the transaxle is a concern of mine though and the 12v battery is getting weak as the voltage after sitting over night is lower than it should be.

So it seems a High Mileage oil or Pennzoil conventional might be a good choice. I might give the Kendal a try as a local store just started stocking that too. Before, at least around here, Kendall was not readily available.
 
Seafoam works great for top cylinder lubrication, fuel system cleanliness and fuel stabilization.
Use on a full tank once per quarter.
 
Decided to give Pennzoil Conventional today with a Pureone filter. Just finished it up tonight so no comment on noise yet. After a couple days of driving I will give some feedback. Thanks again for the feedback.
 
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