I have a 1997 Chevrolet Tahoe with 168,000 miles on it. I think the car oil has never been changed since the the last oil change and filter change when it had 158,000 miles on it. So it has been 10,000 miles with no oil change and no filter change. Is it safe to change the oild and filter now without blowing of the engine because of old oil in it for 10,0000 miles? JOe
TL DR: Change the oil/filter and call it a day.
Yes. Change the oil. You are causing more damage by not changing it. As long as you have kept the oil up to level, you probably haven't suffered too much damage to the engine. 10k miles isn't overly problematic. If you'd said 20k or 25k, then I'd be worried. Change the oil/filter and run it. You may want to run it for a shorter period and change it again, say something around 1k or 1500 miles. Running it for 10k miles isn't good for an engine unless it's spec'd to do it. I'd suspect the engine oil change interval for your Gen I SBC is going to be 3k miles, normally.