This is no joke, but my 1988 351 engine knocks when I first start it up cold for about 5-8 seconds and then quites down.
It makes no noise when started warm.
I am running Castrol 10W-40 "High Mileage" oil right now and purchased a bottle of Slick 50, does anyone have any better ideas than the Slick 50 ??

I assume this noise are the Piston rods and is this normal noise and anything to be worried about ??

 

Is it a "bang" sort of knock like a hammer smacking the side of the engine, or is it more of a "tink" kind of knock, like someone using a large screwdriver to smack it?

Since it goes away after a few seconds and doesn't do it warm, I would think away from the pistons and more along the lines of a lifter tapping, or possibly a rocker arm. There are other options, but those are the most common.

 

How cold is it? And, how many miles on your motor?

It may be that it is taking a few seconds for oil to get to the top of your motor.

 

Fram oil filter by chance?

 

How would a Fram filter be the cause of knocking?

 

I agree... I've had FRAM oil filters on a LOT of vehicles, and never had anything like this happen from their use.

 

I used frams when I first bought my 82 F100. The engine would tick loudly for a few seconds after startup.

According to quite a few people fram filters are junk, the small check valves can get stuck open allowing oil to flow down from the top end of the engine when its shut off, resulting in a dry top end when you start the engine the next morning.

I switched to a motorcraft filter and all was fine, this was on a 300 I6 with 220,000 miles.

 

It is closer to banging sound, though not quite that bad.

I was actually told by a mechanic friend not to use a fram oil filter on this specific engine
because of oil pressure problems. Don't remember what I used !

 

The fram filters found at many parts houses have a very poor check valve assembly that will allow all the oil to drain from the motor overnight. On startup it will take some time for the pump to prime all the lifters again. Simply swapping to a motorcraft FL1A will eliminate these colt start rattles. I have seen this first hand on my trucks, and on our Subaru that I recently did an oil change on. I used a Fram filter because it was all I could find at the time, and now it rattles on cold starts for a few seconds.. something it doesn't do with the Subaru filters.

 

Well color me uninformed... My current oil filters are both Motorcraft, so I should be ok on that. I'll have to remember this, though... I never knew Fram had problems.

 

swap to 10w 30 since its gettin cold out

 

You didn't say how cold it is.. I used to have an issue with cold starts and I used some lucas oil stabilizer and it solved it. It also helps that now I don't plan on putting her through winter again. Maybe she decided to love me for that? Lol.

 

Here in Oklahoma, it is 40 degrees one day and 70 the next, but it does seem to get louder when it is colder and I plan on driving her when we get snow on the ground which is why I bought her.
Is the Lucas better than the Slick 50, as I have not put the Slick in yet ?

 

Try putting a bottle of Lucas Oil Stabilizer in your engine. That stuff is super thick and will stick to everything inside the engine....keeping it lubed up so no dry starts!

 

I would definitely recommend lucas over slick 50, any day.