Got the dreaded piston slap?

[jaslo]

On my 01 pickup that has 87,000 miles I changed the oil out. I used castrol syntec because we had some left in the garage and I wasnt going to let it go to waste. Well after changing that oil out and putting Mobil 1 clean 5000 I have bad engine knock. Is this the so called piston slap? I mean it is really loud for me to hear it in the cab, it doesnt last long, maybe 30 seconds to a minute. My question is, is this bad for the truck? Should I go back to synthetic oil, because maybe the castrol syntec cleaned it out too much? I have always used dino oil except for this last time and now I have the bad knock after changing it out.

[ken1mod]

You are probably not hurting anything as long as the noise disappears when warm.Tolerances are correct with a warm engine and too big when cold.

 

If the noise bothers you, and it would me, go back to your earlier oil. Synthetics tend to be a bit overrated. Dino oils will keep any properly designed engine alive and well way past 200k.

 

Ken

[C & A s Dad]

By any chance, did you change brands or part #s on the filter? If is as loud as you say, it could be possible you have a drain back issue in the filter. Not likely, but possible.

[jaslo]

No, I have used the same oil filter. I use a wix. I have always used dino oil except for last time when I used castrol syntec. I put mobil1 clean 5000, its a dino oil. It just does the loud knocking for the first 30 seconds.

[C & A s Dad]

There should be no issue with the Wix filter. They are great quality. I would agree with Ken, I would go back to your orig oil and change the filter also. If the knock goes away, I would ask the Auto Parts store to warranty the filter. The anit drainback valve in the filter is designed to help hold oil in the oil passages to some degree so the engine starts with some oil already in the system. If the anit drainback valve was not functioning properly it would cause the engine to start with less oil in the system. I have sold Wix filters for over 20 years and have never had this happen but there is always a first time.

 

It is very odd that this would have "simply just happened" at the time of the oil change.

[jaslo]

Or do you think I should go back to synthetic oil? I am thinking maybe the castrol syntec cleaned the engine too well and now using dino oil it knocks? It only knocks at startup though. I have used mobil clean 5000 oil before I used castrol syntec, so that shouldnt be the problem either.

[C & A s Dad]

Sorry, when I said go back to the oil you were using I thought you had been using syn. I really do not feel this contributed to your problem but you could certainly try it.

 

Good luck. I am sure this is bothering you as it would me.

[jaslo]

So you think it would be ok to let changing the oil go, until it is ready to be changed again? Because it only does the knocking whenever the truck is cold. And then it goes away about 30 seconds later. What is everybody's opinion?

[jhm]

I would just change the filter and check/top off the oil. It could just be coincidence that the CSK started when you changed the oil. You may be stuck with it.

[C & A s Dad]

I would agree with jhm. Change the filter, you will need to add about 1/2 qt to 3/4 qt of oil and see if it helps. If it goes away, you will know that you had a filter issue and the Parts store should warranty the filter for you. IMO, if it knocks on one oil, it is going to knock on another as long as the weights are close. For this reason, I would not change the oil until it was ready but I would try the filter.

 

I really hope you find the filter is causing this, but I doubt it.

[jaslo]

Would the knock go away if I use synthetic oil the next time I change the oil?

[C & A s Dad]

In my opinion, I seriously doubt changing the brand of oil or from syn back to dino or vise versa will help. Like I said earlier, if it knocks on one oil, it will likely knock on another also.

[Z71SIERRA]

When I had around 30000 or 40000 miles on my 2002 5.3 I did an oil change and "suddenly" had a start up knock (clatter..tick..whatever). I figured I got the curse but after my next oil change (mobil 1 always) the knock was gone. I retreived the oil filter I that I just took off (a AC Delco) and when I looked close in the filter I could see that the anti drain back valve in the filter was folded over on itself leaving it open. It looked like it happened when it was manufactured. Since then I have been lucky and (knock wood) I have not had the "curse" return. I now spend too much for a Mobil one filter which is overkill but I've never replaced an engine because I used too good oil or filters.