I have a lot of people contact me asking about the recommended oils to use in their Radicals. For many years Radical has recommended using Fuchs Sikolene Pro 4 15w-50 oil for the engine, and Neo Synthetics 75W90 RHD for the Gear drive unit. Note that Neo sells a couple of oils that look similar... you want to get the RHD (Race Heavy Duty).
Recently Radical has partnered with Motul and now also recommend their oils. But I have always used these and they have performed well so I haven't changed. I am sure the Motul is excellent also.
Charley
Recently I talked to Dave Mansfield at Hewland who told me about this new gear oil that they now recommend: the best part is that they say gearbox warmup is no longer required.
https://performanceracingoils.com/content/PDF/Hewland%20UPB%20Le%20Mans%202017.pdf
I had to put in Motul at the last oil change because everyone online was sold out of the Silkolene. I called Radical West in Sonoma CA and they recommended Motul 300V 15W40. It is green colored.
I have been running mobil 1 75/90 LS we been running this for years with great results.
For engine oil, Maxima ProPlus 10w-50 & 20w-50 mixed 50/50. It has been fine according the oil analysis reports.
15w-50 is the recommend weight
The winter rating of motor oil in racing engines doesn't mean much. I'd guess Radical wants 50w oil to provide proper pressure at temperature at racing speeds, and the Motul and Silkolene came as a 15w-50 oil. I doubt there's anything more to it than that.
I got clarification from a friend at the Radical Factory and he confirmed that the the currently recommended engine oil is Motul 300V 15W50 4T Factory Line.
Charley
Yes, that's the recommended oil from the latest SR8 Owner's Manual. It's green in color, and available at Amazon.
Team Stradale's website says this and my car came with a few unopened quarts of Mobil One Racing 4T 10W40. Has anyone used that oil?
"Oil/filter change is approx 7 qts to full. Use Mobil One racing 4T 10/40 full synthetic. This is motorcycle oil (not car oil), use dipstick to verify hot level. Check oil level daily before running and during the day. Look for leaks in between sessions."
Also this:
"Gear box change uses 1.5 liter of redline 75/90 gear oil, change every 6-8 track days."
@gobble, Mobil 1 is an excellent oil and I have used the automotive version in my street cars for many years, but I have never used it in a Radical. Franchesco and his team are extremely knowledgeable and I won’t second guess what they recommend. In fact they are one of the two Radical approved rebuild shops in the US. With that said, I think it would be worth giving Franchesco a call and asking him if that is his current recommendation. I have spoken with the technical experts at the Radical factory about this subject and was told that Silkoline and Motul are the two engine oils (As described in this post) that are recommended by them. They also told me that the factory has tested several gear oils and Neo RHD performs the best.
I’m sure that there are many great oils that can perform adequately, however, I only use the factory tested and recommend fluids.
Charley
I am using the Motul 300V 15W50 4T Factory Line. I am also using Motul for the GDU. It was recommended by Radical Northwest when I purchased the car.
@johnannz off to buy some GDU oil and thinking I'll stick with Motul. However, it looks like there are 3 different levels of Motul Gear Oil. There is 'Motul Motyl Gear', 'Motul Gear 300', and 'Motul Gear 300 LS'. Does anyone know which one is best suited to the Radical GDU?
