Subaru Diesel - Which engine oil ?

Hello everybody,

I have a subaru legacy boxer diesel and today I noticed the oil level is now low.
The manual states '5W-30 C2/C3' oil needs to be used.

Does anybody know which oil I should buy. In the past when I had a petrol WRX, I always use to use the Shell Helix high performance versions.

However, the only shell 5W-30 C2/C3 that I can find is the Shell Helix Ultra Extra. There is also a castrol edge 5W-30 (mentions recommeded for audi/VW) but this is not C2/C3. I also found a mobil version.

If a C2/C3 oil is not used (e.g. if I used the castrol edge) would this cause any damage to the engine ?

Hoth

C2 and C3 are ACEA specifications for oils suited for petrol and diesel engines. C3 being better than C2. Most of these oils will be a synthetic low viscosity oils, and therefore will usually be 5w30 or 0w30

So your right: Shell Helix Ultra thefore is the only Shell oil that fits this criteria.

Castrol "Edge Turbo diesel 0w30" also meets the C3 and the viscosity recomendation, and will be ok. Just take note there are SIX different grades/types of oil under the Castrol "Edge" branding, so don't get them mixed up.

Just for reference, B1, B2, B3 etc. are ACEA specifications for diesel engine oils, whilst A1,A2,A3..etc are petrol engine oils. The C2 and C3 ratings are supposed to be based on B5 or A5, so in theory a B5 rated diesel oil should suffice. Using a non-approved oil proabably won't do any harm, but should the engine ever fail from a lubrication problem and you can't prove that you used the correct oil. Kiss bye bye to any manufacturer's warranty.

Further to the last basically the ACEA C2 and C3 classification refer to the ASH content of the oil.

This is important and is usually specified as the vehicle concerned has a diesel particulate filter as with the Legacy Diesel.

Problems with the filter will arise if correct spec oil isnt used.

I can recommend OPIE OILS. They do an oil recommendation e mail facility if you give them details of your car.

In my case Guy at OPIE OILS recommended a MOTUL OIL for the intermediate oil changes i intend to do at 6000 miles intervals on my Legacy Diesel.

If i remember correctly not near my garage at moment i bought Motul 8100 X CLEAN it is a C3 OIL but i think its a 5w40 rather than a 5w30 but Guy said this would be fine.

Comma OILS i have noticed also do a 5w30 c3 full synthetic which is widely available so do Mobil.

So take your pick.

Thanks for the advice.
Stuart, in the manual on the Legacy diesel, it states a service is only needed at 12000 miles (I have the UK version). Do I need to completely change the oil before that ? or just check every 1000 miles or so and top up as necessary ?

Hoth.

No problem. Personally i wouldnt change the oil before the first service at 12000.

There is a valid school of thought that leaving the original factory fill of oil in for 10/12 or whatever 000"s of miles till the first service is beneficial to the bedding in/running in of the engine.

After that its personal choice as to whether you do more frequent oil changes than at the routine 12000 services.

Some would argue that that is fine for modern engines and technically advanced oils.

Also if your not in the habit of keeping car long then why waste money for someone elses benefit.

I dont keep my cars that long maybe 4/5 years but i rack up high mileages and i normally pass them on to friends or family.

My last three cars are still going strong with all original engines having had no work and between them they have done 535000 miles.

I may be old fashioned but i religiously change oil and filter every 6000 miles.

My legacy diesel has now done 12000 miles in just over 3 months and is going back to the dealer next week for first service. After that i will then change oil filter at 6000 intervals.

Incidentally dont know about yours but in 12000 miles mine has needed a couple of cup fulls of oil if that and that was during first 2000 miles as to be expected.

Now never moves from maximum.

Regards Stuart.