What does everyone (anyone) use for their marine engine. My owners manual recommends Pennzoil 15W40, what's the diff if I use another oil brand with the same grade and certifications?

Personally I HATE pennzoil. I have found that it leaves alot of residue and sludge in the engine. I use Mobil One 15w40. I buy it at Walmart in the gallon jugs for $18 which is the best price I have found anywhere.

I also use Mobile One - Full Synthetic 15W40 (Wal-Mart)

I use Mobil 1 but any major synthetic is fine and beyond that it's not a worry.

Why do folks use synthetic in their boats? Less sludge and residue? Better performance? just curious. I do use mobile1 sythetic in my tow vehicle.

The engines in boats undergo some of the harshest conditions possible. Its like having your daily driver fully loaded going up a hill 247. I have noticed better fuel economy and cleaner looking oil from the use of synthetic. To me its worth it as its just one less thing to worry about and I hate things going wrong on the few days I have to relax.

At how many hours did you start using the synthetic? I thought I read somewhere that recommends to have put at least 100 hrs on your engine before switching from standard to synthetic?

I've used Penzoil 15w 40 for my first two oil changes and in the transmission as recommended. So far the oil coming out looks almost as good as the new stuff going in? No "sludge" or "residues" that I've seen in either of the waste oils. Was thinking of trying the Rotella 15w40 as it is more readily available and I've read others posting on here that say they are using it.

chevron delo 400

Indmar says to wait until 100 hours before going to synthetic. <BR> <BR>I run synthetic in the engine, but does anyone run synthetic in their transmission?

I've run synthetic in transmissions and have had exceptional luck with it. If the tranny uses gear oil or engine oil it's great. I've run in in automatic transmissions and have found it lacking so I switched back to regular ATF products. The synthetic was noisier. <BR> <BR>Cosmo, I started using synthetics in race cars because I was having problems with oil temperature in a couple of applications. The synthetic could handle that better and when I went to Mobil 1 the temperature went down too. I have run many hours of dyno testing as I developed a couple of motors and I am absolutely convinced of the value. Simply you get more power with less wear and better cold starts. If you have a turbo it's even more important. If you have oil leaks you leak more so fix them first.