So there's only 5 more weeks left until my 2004 Discovery SE is paid off and I'll get the title and keys. First thing on my to-do list is premium oil and filter change. I was using Shell Rotella oil with my former D1, but with high mileage and poor mechanical condition from the start I could not determine any benifits of Rotella. Nevertheless I'm going with either Rotella or Royal Purple engine oil for my 2004. Which is better? Which will do more for my 4.6 engine? Price is not a concern when it comes to oil so fill me in on what you think is better and why.

 

The advantage of the Rotella and any other diesel rated oil is cleaning chemistry and the formulation to keep diesel engine soot in solution, so the filter can trap it, rather than making a sludge buildup. The advantage of a synthetic oil is long drain interval. But with an old design engine, internal dirt may be produced more often and you want to drain more often. The high dollar synthetic may push owners to use a long time between chages to save money. I like 5000 mile intervals with don't worry about it cheap oil. And a big honking filter, like the MANN in the tech area write up.

 

Rotella in a T-6 is a great oil, so is the better Royal Purple line.
Whatever you do, use a top line filter, Mobil 1-301, K&N 3001 or the extra large Royal Purple oil filter.
Also, rotate your oil weight if you go thru really cold winters to a 5 or 10W/30 and heavier in the waerm month any where from a 10/40 to a 20/50.

 

But no matter which oil you use, change more often than factory spec. Don't fall for the marketting trap of extended drain intervals. Here's pix of Castrol or Rotella at 3,000 - 5,000 changes 190,000 miles; and three others that were not. Seems like the reddish one was just under 60,000.

 

Are those numbers for the D1 numbers or are the filters the same for the D1 and DII?

Also, what does everyone consider a cold winter? I live in East TN and we get down to teens and few times in single digits but not for more than a few days. It usually runs in the 30's and maybe upper 20's at night for a week or so. It kind of bounces here. I am getting ready to put oil back in mine after using the timing chain kit. I can tell from what I drained out it has not been maintained well from the last owner who only owned it for about 9 months. I would like to put the diesel oil in to clean it real good but don't want to damage it from it being to cold.

Thanks,

 

go with the rotella if it is a dirty as you say you may want to do you first change a little ealier to get all that crap out.

 

I recently did a bunch of research into synthetic, and am now firmly converted to a synthetic user. I also believe that it makes sense to use an extended oil change interval when running synthetic.

The difference is dino oil is a naturly occuring product that is modified to make it a effective motor oil, while synthetic is designed and manufactured solely to be a motor oil. Dino oil is refined from crude, so how clean it is when brand new depends on how effectively you can refine it, but there will always be residual impurities. Meanwhile synthetic is manufactured from scratch, so is a much purer product. So, synthetic flows better, stays cleaner, has fewer impurities in the first place, and is more slippery.

One interesting thing to do is google Blackstone reports on oil, which is what changed my opinion on longer oil change intervals. Blackstone labs will analyze oil and send you a report of your oil's condition, and people often post the results online for others to see. Blackstone routinely finds that any synthetic is still lubricating effectively out past 7k miles, some much further than that.

When I got my Disco, it had Quaker State with 4000 miles on it. When I checked the oil, it was absolutely filthy. I had to drive 700 miles towing a TT to get home. So I went ahead and swapped it and filter for Mobil 1 10w-30. The difference in the way the engine ran was remarkable. I have Mobil 1 in my Corvette, and it has 4000 miles on it. It's still translucent and smells clean. I have 3000 miles on the Amsoil Sig Series in my Nissan Armada, and it looks almost like fresh oil.

If cost is not an issue, there's no question you should run synthetic. The only question is whether to change it at 3000 miles or actually wait til it's actually used up.

 

Thanks. I will know more Tues evening as I am going to be dropping the oil pan so I will be able to see the insides. I just know the oil I drained was black.

 

I don't think anyone questions that the synthetic is better. Now watch, I'll get slammed for that. But it is hard for some of us to swallow when we change often and on top of that, most of us have misc. leaks hear and there. I don't like draining synthetic on a continual basis even if its a small leak

 

I thought the major issue with switching to Rotella was its high zinc content which worked better in these nailheads then the new **** without zinc additives.