thats why i started sea foaming my motor every other oil change once it got up over ~90k miles... i ran 15w50 mobil 1 in my 01 for the first ~60-80k miles... ran like a scalded *** ape. going to switch the '08 over to syn. once its due a change.

 

I'd never put anything thicker than 10w30 in my truck, but thats just me.

 

Oil is oil. Do you think with 15w40 vs 10w30 that my truck wouldn't run? I can get it cheap (read: free), so I run it. I'd run straight 30 if I could get it much cheaper...

The thickness doesn't really matter down where I live. If I pour 5 weight vs 15 weight, I can't tell a difference. In the north, a thinner oil might be worth it.

It only matters that you buy good, name brand oil. It doesn't have to cost a fortune though.

 

I've been using dino oil - castrol 5w30 per the oil cap. But I'm thinking about switching over to the Amsoil oil and filter, it's synthetic and is rated for 25,000 miles or 1 year between oil changes.

 

Hows your crankcase venting system? PCV blocked?

 

There's something fishy going on. I put 200K on a 92 Grand Caravan using 5W30 Havoline oil and it still looked like new inside the engine (I had to replace the oil pan gasket at 190K).

 

I used to run Havoline in my 85 MonteSS before switching to Mobil1, and my engine was spotless. Not sure if they changed their formula since then though. I have a feeling that the "tech" was trying to sell you an oil flush or something like that...that kind of sludge doesn't happen on a maintained engine unless you're using Crisco oil lol.

 

I would check that. Doesnt make sense why your engine is sludged if you use good oil and change it every 3,000 miles.