I just bought a 1998 Discovery 1 with 80,000 miles. I was told by a land rover mechanic to use diesel motor oil since it is thicker and makes the cam shaft wear less. I need to change the oil soon, so should I use diesel oil or regular oil?

 

Either diesel or kendall gt1 or valvoline vr1 oils. Last two comes in 20w50 which is fine until winter time

 

Heavy duty engine oil (HDEO) or AKA diesel oil is great for our push rod engines. That LR mechanic gave you great advice.

I personally run 15w-40 in summer and 5w-40 in winter. Only on the really freakin' cold early mornings (single digit temps) have I seen the oil light stay on for longer than normal upon startup

EDIT: It's not necessarily that being thicker is better, it's the anti-wear and detergent additives which help with lifter wear and keeping the engine clean. If you want to get drunk on oil information, head over to BITOG: www.bobistheoilguy.com

 

It's the ZDDP that our engines need for their flat tappets. Just because it's a diesel oil doesn't mean it's going to be what the tappets need.

 

The only concern I have with the Land Rover engine is sludge, particularly with short-trip driving.

Diesel oils won't benefit it and will cost more unnecessarily. Corvettes are pushrod engines. Do they recommend diesel oils for those?

Flat tappets can possible benefit from more of some additives than modern oils lack. But you won't find those additives in petrol or diesel engine oils because the emmissions regulations are tightening strictly for both.

Nevertheless, the modern oils are far better than what we used to have. I would rather take any current API oil than the best from 15 years ago no matter how much zinc or whatever it had.

 

Also, the brakes are re-done on it, but they seem....iffy. You have to push the pedal all the way down on it to get some braking power. Is this a characteristic of land rover brakes? They were also bled when re-done.

 

HDEOs have higher levels of ZDDP than PCMOs. VOAs prove this.

If your concern is sludge, HDEOs have higher cleaning agents than PCMOs. It would benefit our older LR engines.

Depending on which Corvettes you talking about, HDEO would be fine for it. Roller lifter SBCs didn't come out of the factory until when... mid-90s? I'm rusty on my SBC trivia. All the '50s, '60s, 70s Corvettes with their factory engines would enjoy HDEO.

Cost? Really? Have you priced a decent HDEO lately? It isn't that bad/more expensive.

What additive isn't in a PCMO or a HDEO from which a flat tappet would benefit due to emissions regulations? ZDDP?

 

Times 1000 on the Rotella, its cheap and can be found anywhere.
As for the brakes, no, you should have pedal at the top but it is a heavy truck so it will take longer to stop.

 

I drive my dad's 3/4 ton pickup which is heavier and I get better braking power with that. Do you mean I should have power as soon as the pedal is pushed?

 

Yes, you should start to stop as soon as you push the brake pedal.
If the rubber brake lines at the wheels are bad they will balloon as soon as you press the brake pedal and you will loose stopping power.