diesel engine oil to quiet piston slap.. it works!

[kfy1232]

i know this has probably been discussed a million times but i just wanted to let you guys know that i put in 5 quarts of Valvoline 15W-40 diesel engine oil during my last oil change to see if it would quiet down the piston slap and holy crap it worked.. it's noticeably quieter now, i mean it's still there like if you have the hood open you can hear it but it's more muffled now and i can't really hear it from inside the car like i used to. oh this was on my '98 Legacy GT by the way.

[ooberdoob]

15w40

you put crude oil in your engine...

i'm sure it's quiet :shock:

[MCarp22]

I usually run 15w40 through a car's first oil change when i get it. The diesel oils have badass detergents and stuff.

[Huffer]

Yep, it does work - some fellas over in Europe do it for their Imprezas.

A number of Diesel oils are rated to the same specs as gasoline ones.

[Reason]

I never heard of this, so you guys are saying if one runs 15w40 in their engine for one oil change it will clean it out?

[Huffer]

No, I'm saying if you use a diesel oil that meets the specifications for a gasoline engine, you might quell the piston slap issue.
Specifically, Mobil Delvac.
www.imprezasport.net (http://www.imprezasport.net) has a few threads.

[Sarra]

I thought regular diesel oil has too many detergents for a gasoline engine, and could eat your seals completely away... If it's made to specs for a gasser motor, though, shouldn't be a problem.

[Reason]

Is there anything out there?

[kfy1232]

well the car is running just fine on the diesel oil. i will change back to regular 5w-30 oil at the next oil change to see if the piston slap gets louder again. i'll post here if the diesel oil causes any problems.

[Jedi Taxi]

(this entire subject) :roll:
Honestly, you didn't have to go with a desiel oil. You just had to go with a thicker oil. this problem is an easy problem to stumble upon. Generally, it means either that you have a dirty ass engine, running bad oil, or have weak piston rings (which i highly doubt because you would be seeing FAR more problems if this was the case)

now lets just let the thread die right here.

[Huffer]

Tried the thicker oil - didn't work. Possibly have a dirty ass engine, but I change the oil every 3000 so that's unlikely. I use semi-synthetic oil.

Engine runs like a champ, but is just noisy.

[Jedi Taxi]

Just dont rule out that your engine might be dirty. it doesn't really matter what oil you use (unless its crude, all organic, that stuff makes your engine dirty QUICK). Engines get dirty. Its like aging, it happens. just clean the engine once every 9000 miles (or every 3 months) and it should run like a champ. i know your valve guides, main bearings, piston rod bearings, piston rings, and basically anything the oil touches will appreciate it.

[dodik]

How about Lucas' heavy duty oil stabilizer, i ran it for more than a year in my old BD and am running it now in my H6 works awesome for me.helps with dry starts after oil change and makes your engine run way smoother and quiter. BUT it does not make your oil thicker.

[Jedi Taxi]

the way i am with lucas products is "if it works for ya, props to ya" I have had nothing but bad luck with lucas products. but hey, if it works for you, thats great.

[backpack09]

How about Lucas' heavy duty oil stabilizer, i ran it for more than a year in my old BD and am running it now in my H6 works awesome for me.helps with dry starts after oil change and makes your engine run way smoother and quiter. BUT it does not make your oil thicker.

Why would you think your car needs this?

Good god. This tech forum is rediculous.

How can anyone recommend snake oil or diesel oil for an engine to get rid of a bit of noise? This is not a rebuild in a can. You are not fixing anything. And in the case of lucas products, doing more damage than was already there.
For a bit of background:
http://www.bobistheoilguy.com/images/lucas/lucas.htm

[dodik]

I dont know what he did to that oil with lucas but in my old BD and my new H6 i did not ever see that discoloration or anything else like that. First off there is only certain amount of additive you can add to oil. second i have no idea why that guy added regular lucas to synth oil there is a different lucas product for that and i personally never used it. BUT after my BD got HG "repaired" i had knocking lifter and it was knocking like a horny woodpecker or something and yeah i could've thrown a grand in rebulding heads and all but with lucas it didnt knock as much. it still knocked loud when engine was cold but as soon as it warmed up it almost went away. oil never changed its color and some minor leaks disappeared. AND i am not recomending for any1 to use it in their engines but i DO and WILL use it on my cars.

oh and by the way my car has oil pump not splashing method that that guy used.

[MCarp22]

The bottom line is that the lucas stuff sucks in that test (and in engine applications) because it displaces correctly engineered oil. You reduce the amount of anti-foam, EP anti-wear, etc. that the oil contains, and replace it with base stock that doesn't work very well.

[Huffer]

Good god. This tech forum is rediculous.

How can anyone recommend snake oil or diesel oil for an engine to get rid of a bit of noise?

The information I received is based in part on other people's experiences, and my own staring at the specification label on the oils themselves.
The right oils meet the same specifications as gasoline ones.

A tech forum is to be used to discuss and disseminate myths and truths - not a posturing ground for a person's opinion. If a person isn't open to changing their view or their opinion, then the tech forum isn't for them.

[Reason]

A tech forum is to be used to discuss and disseminate myths and truths - not a posturing ground for a person's opinion. If a person isn't open to changing their view or their opinion, then the tech forum isn't for them.

Money, I can't word it any different. If we can discuss "myth" vs "fact" where can we?

[Sarra]

A tech forum is to be used to discuss and disseminate myths and truths - not a posturing ground for a person's opinion. If a person isn't open to changing their view or their opinion, then the tech forum isn't for them.

Money, I can't word it any different. If we can discuss "myth" vs "fact" where can we?

Na na na na na na na na, Myth Busters!

It's a way to learn. And not do ultra stupid things to your car, like put gasoline in your turn signals because some smartass told you to change your blinker fluid.