New Motor Break-In Period

[RyanWebb0412]

Hey friends,

Well, I've officially put 10 hours on the new-to-me 1995 Cobalt 200! I. LOVE. THIS. BOAT! Haha! So long story short. I bought the boat this spring from a family who had owned it for a long, long time. Last fall they had to put a new motor in it as it had overheated, etc. So it has a fresh rebuild and I'm going through the break-in process. The company that did the rebuild recommends that I use Pennzoil 15W-30 for its first oil change, but my local marine mechanic recommends 5W-30 as we're at altitude (4000 ft ASL). Thought I'd jump on here and see what y'all think! Looking forward to the feedback.

Sidenote: I'm an idiot and last weekend found a freaking sandbar. Thank GOODNESS I did no damage to the outdrive or props. Everything still feels normal. There's a 12 inch rub mark along the v of the hull that I think I'll need to do a gelcoat repair on, but think I'll just wait until the end of the season to do it. Maybe some feedback on that as well would be helpful. I'll add pics later.

[cmattj]

Add an impeller change after your sandbar encounter. Doesn’t take much grit to wipe one out.
Depending on your engine build ( Marinized, Automotive, Shortblock, complete) let’s assume it’s a OEM replacement.
Use the oil “ viscosity weight “ as recommended for that era.
You will find 10-40 to be a better safeguard as long runs and idle oil pressure will remain good.
5-30 was a development in lighter oil ring tension later model engines.

That era would usually want a higher low weight regardless of elevation.
Marine environment with higher moisture and high rpm have different needs.

When in doubt match the cap.