Which oil should i use for piston slap engine? Need advice...

[joehb10]

Hi, I have a lovely 97 mk3 Golf Cl 1. 4 (aex engine code), and it has a lovely loud piston slap. I have owned the car for about 2 months, no problems, no oil consumption issues either, but the slap is there whether hot or cold engine. Im currently running 15w40 semi in the engine, which is one grade above the recommended. I have been thinking about trying 20w50 in the engine to see if that quietens things down a little.

What do you think? Has anyone doe this??

Or am i going to destroy a perfectly good engine?... I just want the slap to quieten down a bit!


Thanks, Joe

[justalex81]

you want some nice thick oil so stop sticking semi synth in it! castrol gtx high mileage used to work a treat on my mk2 valver with 215k on the clock.

either way you should be putting 10w-40 in it

[Wayne]

Would it not be better to fix the engine 

[Len]

Are you sure its piston slap?

I doubt it very much if you are not using any oil.

[Christo77]

Agreed there, the second thing i expected you to say was 'it's using/burning oil'  that would mean a pretty well worn engine with a bit of a smokey haze out of the exhaust pipe..and as wayne says also, fix the engine if that's where you think the problem is..but piston slap'.. are you sure..

Cylinder bores wear and tollerances increase but if your hearing a noise that loud accounting it to piston slap then i doubt the engine would hardly run at all.
Are you not confusing it with tappet noise..or even some other anomoly outside of the engine..!

[joehb10]

Hmm well my mechanic reckoned it was a worn tappet. but I am convinced its a slap. I'll tell you why: when I start the car in the morning, it starts fine, very little slap or tap. Then as it warms over a minute or so, the loud tapping appears. So it only  taps at running temp... what else could cause that?!

The engine is fine. I don't think I would spend money on repairing the noise, as the car is fine. Just wearing and showing its age in the form of the loud tapping....

[Khare]

Do a compression test.

However I'd say it's a tappet. Piston slap would be most heard with the engine cold, not hot.

[Christo77]

I'd say that piston slap is a term used for worn cylinders where the piston can rock slightly in the bores, it's not something you'd hear unless severe damage has taken place..  and if you did hear it to the degree your describing, your bores and piston rings would be surely shot to pieces with bellowing smoke out of the exhaust pipe.

The pistons are going up and down the bores at an incredible rate, the so called slap your talking about is sideways movement remember!  so if you can hear a slap' that loud then the engine would be almost knackered, and would it even run at all..

It must be something else, maybe even a worn small end bearing, has it been starved of oil sometime in it's life...

[Wayne]

Sounds more like a cam follower to be honest.

[thai-wronghorse]

From what ive read here id also say it was the tappets and the reason it gets louder once warmed up is due to the oil getting thinner. The cam may even be worn due to the followers failing due to the increased pressure against the cam lobes.