Answer
May 19, 2025 - 04:12 PM
That actually depends on which exact version of the 2003 Yamaha 70 HP outboard you have. Yamaha produced several variants in that horsepower range, and some were oil-injected, while others required pre-mixing gas and oil manually.
For example:
- The 70TLRB is equipped with Yamaha’s Precision Blend oil injection system, which means you just keep the oil tank filled with 2-stroke marine oil, and the engine mixes it automatically.
- On the other hand, some versions like the 70C or other earlier/manual trim models may require you to pre-mix the fuel and oil yourself — usually at a 50:1 ratio.
So, to be 100% sure, you'd need to check your engine’s exact model code (usually printed on the ID plate near the transom bracket).
That said, the OEM service & repair manual we provide covers both oil-injected and pre-mix variants in detail — including full breakdowns of each lubrication system, maintenance steps, and troubleshooting charts if anything goes wrong.
Definitely a solid resource to have if you want to keep your outboard running right for years to come.
