Engine Oils for TDI's

[Trevor]

I was pondering engine oils recently for the 300TDI, and thought I'd put the question out to our learned group as you folks will know a lot more about this than I.

I typically run a 5W40 synthetic on the Defender. I also change the oil very frequently, at least once a summer if not twice, depending upon how I'm using it. So it won't see more than 2000 miles max between oil changes I don't think.

As I understand it, the synthetics are a good choice due to the added lengevity that type of oil brings. Is there more to it than that though? I don't see myself changing oil less as I just like having a look at the oils and filters frequently as that's often where problems will first start to show up. But does one really need to use a synthetic and incur that added cost, or is a good 15W40 a better option if you are dumping the oil frequently? I guess it just boils down to the question, does synthetic bring more to the table than just longevity?

[binch]

I'm waiting for the venerable Red90 to grace us with is vast knowledge and expertise on this topic.   I'm sure he'll have some good input here.......

But if your defender is a 3 season beast predominantly and you are doing the oil change every 2000miles I would suspect that the Rotella T5 15w40 by the 5 gal pale would be a very good, cost effective alternative.     Your frequent changes is traditionally the sage thing to do though.     But as I say....let's get some input from John

[Red90]

The only way to answer your question is from oil analysis.  That tells you how often the oil needs to be changed.  the limit with any of these oils will be soot levels in the oil.  Once the get above around 1%, the viscosity starts to change.  Most aim for changing around 0.5%.  If you have no other problems with the engine, you can determine the acceptable change intervals based on the soot level rates.  The oils themselves will last much, much longer.  Truck fleets run 100000 mile intervals on the synthetic diesel oils by having secondary filtration to remove soot.  The oils don't break down until somewhere around 150000 miles.

From my own engine, I get around 0.2% soot per 10000 km, which is usually where I do the changes.  So really 15k or 20k would be fine as long as you check to make sure everything is working fine.  But since I don't do a lot of miles, I don't have a need.  The analysis is also useful for spotting other problems.

As far as the 15W-40 goes, it will also be fine at these interval amounts.  It also will not affect wear rates.  There has been a lot of comparison on this.  I would not run it in winter though if you ever do cold starts.  The higher viscosity range is needed for winter cold starts.

There is nothing to be gained from changing the oil sooner.  These are quite modern engines and modern oils.  If you look at an oil analysis for an old tech engine like a Rover V8, you will be shocked to death at the wear metal levels.  Those old engine need the more frequent changes as they are eating themselves and they contaminate the oil with fuel.  As an example, Mark's D1 was running 5 times the wear metal rates to my TDI.

[Trevor]

That's good info John, thanks. Fortunately I dump the oil on the Disco as frequently, and it sounds like it actually needs it. I do only run the Defender during the summer though as it locked away into storage for the winter months.

I think I'll get an oil analysis done though on both, just out of curiosity. Where would you typically go to get that done?

[Red90]

Where would you typically go to get that done?

Finning.  It is around $20.  You pickup the kit from any Finning location and then drop off there.  They email the results and it will track with the vehicle.  Their lab is actually in Edmonchuckles.

http://www.finning.ca/Services/Machine_Services/Machine_Maintenance/Fluid_Analysis/Fluid_Analysis_Services/Default.aspx

[Trevor]

ok, that's easy enough then. Thanks!

[Matt H]

In my 300tdi and in my 5.9 Cummins before that I used a mineral 15-40 Diesel oil and change it every 5,000km or around the 3-5 month mark. I also run 15-40 in The Mighty Range Rover V8 and change it every 3 months regardless of Mileage.

At work we run the Heavy trucks 7,000km or specific hours between changes with Duron oil. Same with the light duty fleet (7.3-6.0l diesels). My F550 Service Truck with the Ford 6.7L has the same intervals but with 10-30 oil. Amazingly it runs so clean the oil stays a golden brown colour until oil change time.

The problem with sticking a time and mileage figure on anything is a vehicle's individual engine condition and operating situation. Summer, winter, filtration, fuel quality, idle time etc can all influence oil life. The main reason I stick to the 5-3 schedule is it's easy to remember, always catches changing seasons and operating conditions and gives me a regular preventative maintenance check (grease, worn component checks, fluids, belts etc). 

I suppose I could leave it longer.........but I don't.