Cold start sound of low compressoin?

[12guns]

I bought my 2k Cruiser with 151k miles. Changed the oil to M1 Synthetic as soon as I got home. The oil that came out was clean and I have had NO issues over the past 10k miles.
It does not burn a drop of oil and I just collected an oil sample to send off to Blackstone, which will help answer my quesion...which is this:
Has anyone else noticed an odd sound when starting cold? I'm not talking about the common valve chatter. This is more like a motor with low compression, where you can't hear each cylinder hit like on a warmer start. Once the motor warms up, it sound perfectly normal when starting. Kind of weird, I didn't think much of it, and it seemed to have happened on colder mornings only.
Now that I just changed my oil, the odd noise is gone, for now.
Again, it doesn't burn any oil and runs great, I just have not noticed that in any other vehicles before. I assumed and still assume it is fairly normal, but wanted to ask anyway.
I ran the M1 oil 10k miles and might have pushed too far w/o having a sample tested on this specific motor, however my 4.7 4runner could go well over 10k miles.
I tend to hear noises and issues that most people would never notice, so maybe it's just me. Any thoughts?

 

[OregonLC]

It's piston slap. They all have it to a certain degree. For me it's below 40F that I start to hear it. Noise persists longer the colder that it is. Same thing happens on our ES350. Has to do with different expansion rates of materials. If you really want to hear some cold start noises try my OBXT at 25F.

Don't worry, nothing is wrong. The 2UZ will still love you longer than you'll love it.

 

[04UZJ100]

The 2UZ is notorious for making unusual sounds when cold. Both of mine do.

What filter were you using in your 4R for extended intervals and did you have an analysis done?

I'm currently using M1 Synthetic and the M1209 extended performance filter but have a mental issue going past 8k. And that's 95% highway.

 

[12guns]

Thanks for the replies.
I did have an analysis done, twice. Both times I had AL show up slightly above average, however it wasn't enough to worrry too much about. It had 140k or so miles on it.
I ran Penzoil Platinum and Penzoil Ultra. As for the filter, I let it go the full 10k w/o changing it. I used different filters, not knowing which was best. I went through K&N, Bosch, Purelator Pure One over a few oil changes if I remember right.

I know our 4.7's are easy on the oil, so I hope I'll be able to run 10k on the LC, however the main reason I did so on my 4runner is the fact that the skid plate had to be dropped to change the oil filter. The LC is much easier, thankfully.