oil are what

Well I have this 1999 g m c suburban 5.7 v8 350 it has 204000 miles on it an I have had it since 27000 mile on it changed the oil every 3000 miles but now it sound kind of rough I use 5w30 castrol high mile motor oil but the oil looks good but it sound like the lifters or push rods taping lately when its sitting still would a 10w30 oil help thanks for your time an your help

Did your oil pressure drop slightly (like 5 lbs) as the noises appeared? Running conventional oil, you are about at the mileage where ring and bore wear begin to show up.

I've been a Castrol guy myself for 40 years. I have had good luck substituting Lucas Oil Supplement for one quart of oil at each oil change, bringing the oil pressure back up and getting perhaps another 100,000 miles.

I ran my '90 sub 350 on 10-30 GTX for a bit over 200,000 before switching to same weight Syntec Blend, then to full Syntec about 50,000 miles later. The Syntec tends to be a bit "thinner" than same weight conventional, so I tried the Lucas. It ran almost like new until I decided to retire/replace the engine at 370,000 for non-lubrication issues.

If you switch to a full synthetic oil you can at least double your drains to 6-7,000 miles so the higher oil price is canceled out plus you only buy half as many filters.