Question for Tom-NorthCenTX

In December of last year you replied to my post "Truck using oil" saying:

"Your warm-up knocking is piston slap, as someone said below. Change your engine oil and filter. Use Mobil One 5W30 or 10W30 as you prefer. This WILL STOP the poston slapping you are hearing, and stop its long term bad effects. Seen it work time after time. Try it and post back."

My truck is due an oil change now and this one will last into cold weather so I'm ready to try your suggestion. But I'm wondering were you referring to conventional or synthetic oil?

mobil one is synthetic

Thanks, I didn't know that all Mobil One was synthetic. Well, I'll try it this time. I've been a conventional kinda guy. Never really bought into the hype of synthetic.

If I remember correctly, the original post was probably about a General Motors 4.3 L V-6. They tended to have piston slap at cold startup with conventional oil, and with most synthetic products. Mobil One full synthetic and a new oil filter would stop them from piston slapping. I had a GMC Jimmy S-15 4.3 V6, kept it from new in 90 until about 2000 when I sold it to my neighbor. Told him I always used Mobil One, but he tried to tight-wad it with conventional oil. Started having piston slap, conplained, tried Mobil One, stopped it. Tom

Thanks. I didn't know Mobil One was only synthetic. I'm a cheepo too but I'll try it this time and if it works for me I'll be sold on it. Mine is the 4.8 V8 (2001 GMC Sierra). I'm told piston slap is common on cold starts.

I was never into synthetic stuff, either- until I had a Toyota that started using a little oil. Neighbor was an Amsoil franchisee, and he started preaching the wonders of Amsoil. I finally bought it, more to shut him up than any thought that it would actually help.

He told me it would stop the oil consumption, and that I would have to re-adjust the idle speed after 50 miles or so, because Amsoil lubricated so much better that it would reduce friction and idle speed would increase. Whatta crock, I thought- but he was right on both counts.

That was 30 years ago- don't know if the stuff still works as good (or if conventional oil technology has caught up with it).

I guess I'll find out. I found the Mobile One at Sprallmart. Better price than anywhere else but like usual only a couple human cashiers open and 3 of the 4 self checkouts were broken.

I just got the regular Mobile One not the high mileage, extended performance, advanced fuel economy, or I think there was another too. A 5+ quart was $26.48 and the extra quart I needed was 6.47. Then I waded through all the brands and sub-brands of filters and settled on ACDelco because the size of the filter was larger (assume larger capacity not necessarily better filtration) and it said it had the anti-drain back valve. Fram had 3 sub-brands ranging from $4 to $12!

Maybe I'll get better mileage? I doubt it. Then again unless the difference is really significant I will not notice as I gave up constantly calculating it--too depressing. I know with a lot of idling and slow neighborhood driving during some volunteer work I was doing awhile back it got 15. I think when I was last driving to work it ran 16 to 17. I know the best I ever got was 19.9. That was a whole tank of of gas used and essentially only highway driving.

I'll note the idle speed better now. I'll change the oil tomorrow probably.