how often should you change oil in 454 big block,

I do mine between 20 and 25 hours. Depending on how hard I run them in that oil change period.. Oil is cheap.

What motors do you have? I run synthetic and change them every 30 hours. So for those that know me in the last 6 seasons I have done one oil change.

20 hours

I have a SBC but run it pretty hard (alot of wake boarding). I run conventional oil and change it about 20 hrs. Sent a sample in and they said it was nearly used up. Figure oil is cheap.

Where can a person send the oil in to be sampled? How much do you send and what is the approximate cost?

Thanks
SAR

Intervals can depend on what oil you use. I personally used AMSOIL and change once a season, which is about 50-60 hours.

Analysis, I use "Oil Analysis Lab" in Spokane, Washington. My last years analysis with 53 hours on the oil was still cleaner and stronger than Merc 25w-40 out of the bottle. I have twin 496hos. The tests cost $15, and take about a week to ten days to get back.

Try Blackstone Labs. I have been using them for years.

http://www.blackstone-labs.com/

Email them and they will send you free sample and shipping kits with instructions etc.... the reports are really snazzy and very detailed. Cost is about $22