I’m a newbie to this forum. I’ve been lurking for a bit and decided to toss in a question. First, I’ll throw in a bit of an intro: I’m not new to synthetics and have a bit of knowledge about lubricating oils. I have used synthetics since 93 on a GM 350. It is gone after 150K miles of faithful service. I currently run synthetics in about everything I own. I am a fan of Mobil products but have used Amsoil in a few applications. I run Mobile V-twin in the Harley with 75-90 in the trans. (I’m thinking about 10-40 in the primary on the next change). I have a 6.2 diesel with 350K on it. Motor fresh @ 120K Mystic 15-50 to 340K now using Delvac1. First analysis looked great with 6K on the oil. Mobil 1 in the trans and rear. GMC 6.0 with M1 in the engine, changing the rest soon. Ok now to the question. I’ve played with Amsoil 20-50 racing in an 360ci alcohol injected Dirt Sprint Car engine. On the dyno, a change from 25-50 Penz to 20-50 Amsoil reflected a gain in HP. Amsoil was used without failure for a couple of seasons, but we did see some failures with the dino after that. Based on the previous success we had with the synthetic on the other car, we are thinking about going that route on a different car. With some of the reading/research I have done, I am thinking about going with 5-40 Delvac1. Other options include a 0-40 or even a 0-30 I am worried about shear with the wide gap in the low-high viscosity (isn’t delvac 1 close to being a 50w). With a dry sump oiling system, the oil makes quite a few passes through the pump. It is pumped to a holding tank and then a second time back to the engine. The goal is a gain in horsepower, better reliability and possibly extended use of the oil. We would like to run it 3 to 6 races (approx 30-50 laps) per change with a filter change/inspection every 1 to 2 weeks. Considering we are running on dirt and wanting to extend the oil life, a close watch of the oil though analysis is in order. We plan on initially processing a sample each week to get a good baseline going. Any comments/suggestions? Sprintman? Dragboat? Thanks!