Shorter OCI for flat-tappet motors?

[FastSUV]

5k fine on flat-tappet 4.0L? I know I have asked this before in a "round about" way, but I saw that other post where the guy said the Land Rover owners insist that 5k is max for flat-tappets?

Any input?

Assuming 10w30 oil in either conventional or synthetic blend will be used. I will be doing the next fill with a very robust HDEO oil, but lets just say SM-oil for the sake of argument.

 

[StevieC]

Regular valve springs (not performance) will do just fine with today's oils for 3K miles, if you want to go more get a used oil analysis and look at the ZDDP levels.

High pressure valve springs will shorten this interval by half. I would recommend a ZDDP additive in this application.

In both application I would recommend a synthetic over a dino for the higher PSI film strength you get with syns.

 

[sven98]

The Land Rover V8 is a oddball. They sludge up very quickly and eat camshafts for breakfast. Plus its an all aluminum motor developed by GM (Buick) in the early 60s. Thats why teh 5k OCI max.

 

[lipadj46]

Many of us Discovery guys use "walmart" oils with high zddp concentrations such as Mobil 1 15w-50 / 10w-40 High Mileage / 5w30 EP / 0w-40 or Rotella 15w40 / 5w-40 or castrol syntec 20w-50 / 5w-40 even Pennzoil Premium 10w30 / 5w30 etc for 5k OCIs...

Obviously Redline, Royal Purple, Amsoil all are great too. I am in the process of taking some samples for used oil analysis to see how far I can push Rotella 5w-40.

 

[Petrou]

that is a cool motor, how long have you been on that change of rotella 5-40