The performance and longevity of J-Series engines largely depend on a variety of factors, with oil viscosity playing a pivotal role. In this article, we’ll delve a little into the importance of oil viscosity for J-Series engines and its connection to horsepower ratings.
**Understanding the Role of Oil Viscosity**
Oil viscosity is a key factor in maintaining the health and performance of a J-Series engine. The viscosity of engine oil dictates its flow characteristics and ability to provide proper lubrication under varying conditions. For J-Series engines, specific oil viscosity ratings, like 0W-20 or 5W-20, are recommended by the manufacturer to ensure optimal engine performance, but when it comes to overall performance sometimes a thicker viscosity oil comes into play.
The first number in the viscosity rating indicates the oil’s flow characteristics in cold conditions (5W), while the second number signifies its behavior at higher or operating temperatures (20 or 30). Achieving the right viscosity ensures effective lubrication, minimizes friction, and reduces wear and tear on engine components. This, in turn, contributes to a healthy engine and optimized performance. There are also a few factors that play into an oil’s role within the engine, with viscosity being the largest . Oil in its simplest form acts as a barrier or cushion between two metal parts, with metal on metal obviously not being good. If you have ever heard someone say they found “gold flakes” in their oil, in that case the rods and crank journals have worn enough into the bearing to shed away the upper layers and have made its way down to the copper layer of the bearing – AKA worn bearings. This can come with age or usages, but usually here at HLP Products and with the high horsepower J-series engines we work with, those “Gold Flakes” usually means the engine load (horsepower) has out performed the bearing clearances or oil capabilities, usually in the form of the oils weight (thickness) or ability to maintain that “cushion” between metal parts. The higher the load capacity, rpm or horsepower exerted onto the engine usually means the more compression load the oil is having to fight. A thinner 20 weight oil may not have the load capabilities required for your particular setup, where in that case a thicker 30 weight oil may come into play. This is why here at HLP Products with any customer’s engine or HLP In-House Built J-Series Performance Engine, we usually end up suggesting or supplying the customer with a thicker 30 or 40 weight oil, depending on their application, usage and horsepower rating. Personally, here at HLP Products and since Bertha (our HLP R&D / Test 550whp Turbo J35A7 7th Gen Accord) went over the 100k mile mark, we switched the oil out from the stock 0W-20 oil to a thicker full synthetic 0W-30, 5w-30 or 10W-30 (again the second number being the “hot” or operating viscosity of the oil). While we reside here in Florida, the “W” winter or cold weight did not factor as much into our oil choice, we were more concerned about the operating viscosity of the oil.
In stock form the J-Series engine calls for 0W-20 or 5w-20 weight oil, which is very thin, low viscosity (thickness) and has very little drag on the rotating assembly. Honda’s ultimate goal was efficiency and MPG (mile per gallon) which was achieved with the thin 0W-20 weight oil suggested. In compliance with the thin viscosity oil also came tight tolerances on the rod and main bearing clearances. A heavy 50 weight oil would not operate the same in the tight oem clearances as the 20 weight oil. However, as these engines age and parts wear in, so do the bearing clearances, with usually them widening or getting larger. In turn, the thinner oem 20 weight oil has a much harder job creating and maintaining that oil cushion it requires in order to keep the rod and bearing separated. This is where a thicker viscosity oil would come into play.
If you had to boil this down to a rule of thumb and pertaining strictly to the J-series engine platform, we have found these rules to suit our and our customers’ needs the best. While there is some horsepower to be gained from a thinner operating viscosity of oil, the differences are negligible and are far outweighed by the reassurance , load capabilities and benefits of a thicker viscosity oil in your wider bearing clearance J-series engine, regardless if it’s from age or horsepower load.