However, generally speaking, for engines common in that era, a straight 30 weight oil (like SAE 30) or a multi-grade oil such as SAE 10W-30 or 10W-40 would likely be suitable. These are common and readily available. Always check your owner's manual for the *recommended* viscosity and API service classification (like SG, SH, etc. - older standards). The manual will list the manufacturer's specific recommendations which are crucial for engine longevity.
Do not solely rely on this information. Find your owner's manual (or a digital copy online) and use that as your definitive guide. Using the wrong oil can seriously damage your engine.
