What type of motor oil

I have 2 Volvo Pentas 2004 5.7

I have 2 Volvo Pentas 2004 5.7 GI-E in my 322 Monterey. What type of motor oil should I use. I believe the fill cap says SAE 30. I can't find it anywhere. Most stores have multi vis 10w-30 or 5w-30

I believe in running a high qu

I believe in running a high quality 15W40 oil in marine engines.

any hardware store will have S

any hardware store will have SAE30. There's a few million lawn mowers that all run on 30. Walmart has it in my neighbourhood.

"I believe your owners manual

"I believe your owners manual will specify a single weight (SAE30), SYNTHETIC oil for this application; not something you're likely to find in a hardware store - or Walmart. After doing some investigation, I discovered that there is not a single automobile application for single weight synthetic motor oil - and therefore, no one makes it.

You have 2 choices: 1) Find a local marine supply store (like West Marine or Boater's world) or the dealer from which the boat was purchased. These will all have a synthetic SAE30 marine oil (Volvo even brands a synthetic SAE30 motor oil, but it's not cheap.) 2) Multiweight oils use various viscosity modifiers to make them thinner (less viscous) than they otherwise would be when cold (the first number in a multi-weight oil) and thicker (more viscous) than they othewise would be when hot (the second number). According to the technical help at Mobil 1, their 10W30 contains no viscosity modifiers and is suitable for this application. Mobil 1 is easy to find at any auto parts store, even Walmart and Costco.

I don't know what other differences might exist in a marine engine or whether the detergents and other additives might be different for a marine engine oil. The engine block is, afterall, the same, stock GM 350ci (5.7L) that's in my Suburban, and millions of other GM cars and trucks. However, the conditions a marine engine is subjected to are certainly different than an automobile engine.

So, I make an annual trip to my local Volvo-Penta dealer and purchase the Volvo branded oil, oil filter and fuel separating filter. Costs a few $$ more, but heck, it's only once a year, and why take the risk?"