Best oil for a 53-plate Subaru Forester XT

Lashout_UK · 21 Jun 2017 at 12:45

Found myself randomly acquiring a Forester (2.0-litre turbo XT) which was recently serviced by Robert Clark Motorsport.

The service department there has filled the engine with high-end Castrol, albeit in 10W-60 spec – which seems way too thick, bearing mind that the OEM recommendation is 5W-30/5W-40 or similar. Historically, it's always had 5W-40 Titan Race Pro S, judging by the history and the previous owners' feedback.

Question is, should I be looking to immediately dump the 10W-60? Few seem to use it, and it seems very thick. Can't be doing the oil pump (or the engine's output and temperature) many favours. It is a high-mileage example, though, having racked up 156,000 miles – which is perhaps why RCM opted for the oil?

Being my first foray into Subarus, the territory is a little unknown – and, as is usually the case, there are about 30 different answers everywhere I look. So, thought I'd add a few more to the pile... figure someone here has owned one and been through the above before!

sovietspybob · 21 Jun 2017 at 13:03

A lot of Impreza lads run 10W-60 BUT from my understanding that's only for heavy track work, i only ever used 5W-40 even when i tracked mine. I always thought it was way too think and so far from the manufactures recommended unless you're beating the hell out of it and getting it super hot.

Saying that Roger Clark is seemingly well respected in the community but i don't know how much of it is just a circle jerk as you get in single marque communities. The stuff they sell looks nice quality but to me seems so ridiculously expensive for what it is, £250 quid for a fuel pump in a posh box, yeah whatever..

ScoobyDoo69 · 21 Jun 2017 at 13:26

I'd still say that 10W-60 is too thick, but it has been recommended to me in the past. Mileage could well be a concern hence RCM's choice?

I'm in the 10W-40 or 10W-50 club personally. Titan Race Pro S is what I use too.

Lashout_UK · 21 Jun 2017 at 14:21

Thanks, ScoobyDoo69 and sovietspybob. I may drop the 10W-60 in due course, then (it is several months old now, anyway) and sling in 5W-40 or 10W-40 – seeing as the former was what it lived on previously.

Engine is beautifully smooth so hopefully it's not causing it excessive grief, either way, but I'd prefer to go back to the thinner oil if reasonable.

Also, pictures!

ScoobyDoo69 · 21 Jun 2017 at 14:46

Always had a soft spot for these. Looks nice in the blue and grey/bronze finish

The Running Man · 21 Jun 2017 at 15:10

Maybe they didn't want you to think it was drinking oil so put something thick in there?

Freefaller · 21 Jun 2017 at 15:21

Looks like a tidy example for the mileage.

Lashout_UK · 21 Jun 2017 at 15:41

The Running Man said:
Maybe they didn't want you to think it was drinking oil so put something thick in there?

I don't think so (although you never know) – it's absolutely on the money in all other respects, so I think it was just a matter of their preference. It did previously have 10W-40 in it but when it went in for a service RCM (without any input) refilled it with 10W-60.

It does appear in recommendations for high-speed track use in H4s (including mentions from them), but that's about it. Not entirely appropriate for the road, methinks.

Yea, Freefaller, definitely – even the AC works! No knocks or rattles, feels very tight. Been maintained by enthusiasts, which no doubt helps.

Kaeo · 21 Jun 2017 at 19:51

10w60 will take days to warm up. Be extra careful during the first 5-10 or so miles while you use it. Personally I'd chuck it and go back to 5w40. Very much the wrong oil to be using in that car.

Lashout_UK · 21 Jun 2017 at 21:33

Thanks, Kaeo - thought as much. Think I'll probably return it to the 5W-40 that it'd been run on before.

Simon · 21 Jun 2017 at 22:13

10W-60 will be fine in this weather. Would leave it in until winter if you are worried but can't see an issue if you let it warm up

Lashout_UK · 21 Jun 2017 at 22:16

Cheers, Simon. Interesting. I'll probably still drop it at some point, as it's got some miles on it now - it'll bug me, otherwise, despite it seemingly not giving it any grief.

Phil W · 21 Jun 2017 at 22:17

My Impreza runs 10W-50. Not sure how relevant it is but it's 350bhp.

It's what was in there when I had it and it's what I continue to use.

agw_01 · 21 Jun 2017 at 22:31

The previous owner of my STi took it to Richard Henry in Bradford who ran 10w60. I stick to 5w40 myself, another Titan Pro Race S user.

I have been tempted to switch to using 10w40 in the summer and 5w40 in the winter.

Dr Who · 23 Jun 2017 at 14:19

Simon said:
10W-60 will be fine in this weather. Would leave it in until winter if you are worried but can't see an issue if you let it warm up

Was going to say the same, it was what I used in my Forester S/Tb in Cyprus. Winter you can swap to a 5w-40 if required.

Lashout_UK · 23 Jun 2017 at 21:31

Thanks, Dr Who. I've ordered a filter and some 5W-40 from Opie, so I'll probably sling that in soon. It's due a change, anyway.