Simon420R Posted February 10, 2023 Share Posted February 10, 2023 I've been reading the discussions on oil temperature issues on the 420R with interest. I'm getting my new (to me) 2018 420R serviced soon and I was wondering if there's a general consensus on the best engine oil to use. I've usually favoured Millers and was thinking of going with their CFS 5w40 NT+. Any thoughts? If the oil is failing to reach the desired temperature would people suggest going for a lower viscosity? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted February 11, 2023 Share Posted February 11, 2023 Depends on climate and how and when you intend to use your car. Given the well-cooled oil on a street-driven 420R, a thinner oil would be reasonable I suppose. I'm running the cc-recommended Motul sport 5/50, but I have considered other options myself. Given that most of my miles are hard track miles, I've considered "upgrading" to a more racy oil like the 300V. However, given that I still drive it to the track on some cold mornings, and that my car spends a lot of time idling in the paddock trying to get heat into it, I worry about fuel dilution so I think running the thicker, wider-grade 5/50 makes sense for me. I'm still open to other options though. None of the car failures I've experienced thus far have been oil related, and I doubt they will be for some time, if ever... Link to comment Share on other sites More sharing options...
Simon420R Posted February 11, 2023 Author Share Posted February 11, 2023 Thanks for the reply. I should have mentioned that the vast majority of driving will be spirited road use with the occasional track day. Link to comment Share on other sites More sharing options...
MTW Posted February 11, 2023 Share Posted February 11, 2023 I run millers CFS 5w40 NT+ on road and track Link to comment Share on other sites More sharing options...
Simon420R Posted February 11, 2023 Author Share Posted February 11, 2023 I've used that for years in previous cars and figured it would be a good option for the Seven. Glad to hear you're using it with no problems. Link to comment Share on other sites More sharing options...
MTW Posted February 11, 2023 Share Posted February 11, 2023 Yea likewise, I figured people are always complaining about low oil temp but running a thick oil that pretty much only Caterham recommends. I have asked two Caterham race teams about this when my car was with them, both said 5w40 is fine for a road and track car, one of them said they only used 5w30 in their 420r race cars. Also SBD recommendeds 5w40 for their tuned Duratecs. So I'm happy with that! Link to comment Share on other sites More sharing options...
Simon420R Posted February 11, 2023 Author Share Posted February 11, 2023 Yep, they sound like good recommendations to me. Link to comment Share on other sites More sharing options...
SKC Posted February 11, 2023 Share Posted February 11, 2023 Hi Simon,I'd recommend blanking off the oil cooler with tape, fit a oil to water heat exchanger and possibly a dual oil pressure / oil temperature gauge and run 10w60 oil. When on track, keep an eye on oil temperature. If oil gets above 110 degrees, remove one strip of tape. If it's still getting this hot, remove both strips. But when back on the road, cover the cooler again. We've seen these cars struggle to get much above 65 degrees oil temp on the road. The oil is not in it's operating window at this temperature and will be causing premature engine wear.All proven, all works just fineRegardsSKC*byebye* Link to comment Share on other sites More sharing options...
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