02 silverado,switch to syn motor oil?

[crazy longhorn]

02/4.8, she runs good, no smoke or leaks but has 170,000 on the clock. I am looking to take care of some cold start noise.Would it be a no no, to switch to synthetic oil at this point? Longhorn

[truckdude239]

Swaping oil will not get rid of the nosie my 02 burb with 5.3 has synthetic in it and it still knocks and slaps till it is warmed up.

[allengator]

I think MOST 5.3 Vortecs of this era have cold start piston slap...

and I agree, changing oil will not help

[crazy longhorn]

Thanks guys....yes that 'double knock", is for sure a a slappy piston I just did the "dino" Castrol GTX 10 w 30, & added a pint of Lucas, with a pf61 AC filter. I still have the piston slap cold, but she runs more quiet warm. Longhorn

[68c10airstream]

Fixed a few cold morning piston slaps by cleaning injectors with a gm injection cleaner mixed with gas 50/50. This fix only works on ls engines that didn't slap cold when new. What happens as they age is this;
carbon build up on the sides of the piston just above the top ring land causes the piston upper area to drag in the bore cold and causes the piston to cock back and forth, hence the piston slap or cluck.
My 5.3 did it every year until I cleaned the injectors about mid summer and would start to return in about a month or two. This engine burned a little oil which I think added to it. Once I rebuilt it problem gone.
My injection cleaning equipment I made from an a/c accumulator (receiver/drier) that I cut in half and removed the guts and rewelded it up, added a r12 Schrader so I could pressurize it with regulated air, and welded shut a line that used to thread into the side of it. I remove the line, pour the 50/50 concoction inside it, thread the line back on, pressurize it and hook a line to the bottom of it (another r12 Schrader added here) to the fuel rail

About 30 minutes of idling and all is well again. I did this the day I took the 5.3 apart to find the oil burning causes and the combustion chambers and pistons looked like new.

Cleaning the injectors and throttle body yearly gives me the best throttle response and mileage. The gm cleaner is about $16.00 list I think.

[427Carl]

My 07 5.3 Suburban used 3 litres of oil per 5000KM on synthetic (from 42,000 to 170,000KM)
I switched to reg Dyno oil and it now uses 1/2 litre per 5000km go figure

We had a Cummins (at work) fail Turbo and block at 146,km on Synthetic,

and have a 2010 Cummins with 955,000km on 15w40 Shell reg oil (never apart)

That why I switched my Suburban.......

[1976K5CHALET]

I can here piston slap on the left side of my 6.0. Not terribly bad. However at idle...in gear its enough to trigger the knock sensor and give me a less than smooth idle.

[Daubs]

Been running Mobile 1 in my 04 2500HD since i purchased new. It has the 8.1L 496 Big Block. Has cold start piston slap. Dealership did some work, but could never get to quiet down. Offered to replace my short block, but warned it would probably slap again in future. They extended the warranty to 75k miles on the engine. It has 110k now, and still cold start knocks...but quiets down after 30 seconds or so. Love the truck. It's not been a problem for me.