Oils ain't Oils, Harry. Fuel use by 2006 N/A Forester

Ratbag

Ratbag

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Joined
Jan 1, 2012
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Location
Bayside, Melbourne, Vic
Car Year
MY06, MY10
Car Model
Forester SG & SH
Transmission
5MT/DR & 4EAT Sports
Gidday Folks

Being somewhat compulsive about keeping vehicle log books (and only in small part for tax reasons ... :lol:), I have been keeping an eye on the fuel usage of my new baby.

A bit of background.

I knew it would be more thirsty than my 1.8L Impreza. Goes without saying, really.

I have read many posts about using fully synthetic oils with Subaru engines (and probably applies to almost every other modern engine design - i.e. since about 1990 ... ), so thought I would give it a try.

At my last oil change, I got Ross to use Shell Helix Ultra 5W~40
( https://lubematch.shell.com.au/reco...=35660&site=58&region=281&language=5&brand=67 ).
This is Shell's bottom of the line fully synthetic oil. Ross said, "We generally only use that stuff for cars like Ferraris, John".

Using this oil instead of Shell's Helix "synthetic technology oil" added about $25 to the service; which cost about $180 in total.

My fuel warning light came on today at 483 kms after my last fill. I know from experience that my car has almost exactly 10L left in the tank at this point. Predictable and accurate as heck. Our Camry waffles on for about 10 kms before the FWL comes on and stays on. At this point it has about 7.5~8L in the tank. Not so with Roo2. It comes on and stays on after one flicker and about 1 kilometre.

I thought: "Hello. This is getting better fuel economy than I have got so far ... ". So sat down and did a quick spreadsheet.

[EDIT] I have now filled the tank at 497 kms. It took 52.55 L; giving 10.57 L/100 kms for this latest tankful. Some of this was with 4 adults on board (about 30 kms) and some with 2 adults (about 200 kms). The rest with me and miscellaneous kit, but not even lightly loaded, by any means. This is around 0.54 L/100 kms improvement.

I am not a lead-footed driver (not these days; nor is it necessary in this vehicle - I drive it far more gently than I needed to drive Roo1 to achieve the same result ... ). Nor do I muck around. 6000 rpm+ occurs moderately frequently in first and second in particular.
[End edit]

Up to the oil change, I have averaged 11.26725 L/100 kms over (only) 797 kms. This included the Bunyip SP nightmare.
My next tank included the Noojee day trip, which had some pretty hard going in it, but I returned 11.32 L/100 kms on that tank. Considering that I had to drive home without using 5th due to my left arm & shoulder being a tad buggered (about 2 hours drive), that seems fair enough.

This gives an average of 10.86 L/100 kms (including the off-roading around Noojee).

The next tank (current) has returned 10.41 L/100 kms, including about 50:50 city:highway driving.

[EDIT] Actually, 10.57 L/100 kms. And on more reflection, I actually did around 160 kms on freeways/open road. i.e. around 32% open road and 68% city and speed constrained driving [end edit]

This represents an improvement in fuel economy of 0.4 L/100 kms since changing to fully synthetic oil. At 12,500 kms between oil changes, this represents a saving of about $70 in fuel between oil changes.

My first tank of fuel returned 11.11 L/100 kms with no off-road use.
My current tank is looking more like 10.42 L/100 kms for the same kind of usage.

The latter represents a more general fuel saving of around 0.7 L/100 kms, or around $122 saved between services.

It also appears from my reading that the fuel savings benefits only become stable (maximised) after several oil changes.

Has anyone else had a similar experience?

I will keep this thread updated from time to time.
 
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That's actually quite interesting.

I am running Shell Helix 20w50 due to my burning oil. Trying to slow down the consumption abit. Although its made no difference compared to the usual 15w40 I usually run.
I have how ever noticed worser fuel economy. I average 400-450km to a tank. So around 10-14l per 100km. But my engine has a few little things that need doing.

Im not suprised the fully synthetic has made a difference. Both Nachaluva and I are running fully synthetic gearbox oil both with huge improvements to our old boxes so I can only imagine how it would help the engine.
What about power, slightly more responsive or not?

Taza
 
Oils can make differences. If you run a lighter grade oil in turbo engines, you will probably notice a bigger gain. The downside there is the oils cannot deal with the heat, they break down and there goes another engine. Of course, it depends on how hard you push the engine.Anyway- can anyone with a 2.5 NA beat my 39MPG from last month- I was not driving for economy?
 
True. I wonder though what I would get if I could ever be bothered to drive for economy. But driving for economy is too painful.
 
Rally said:
True. I wonder though what I would get if I could ever be bothered to drive for economy. But driving for economy is too painful.
Click to expand...

Probably not :lol: I managed once for city/country town Geraldton driving and got 7.9l per 100km. 650km to the tank, so I couldn't complain :raspberry:
It was the worst (slowest) 650km ive ever done!
 
Rally said:
I wonder though what I would get if I could ever be bothered to drive for economy. But driving for economy is too painful.
Click to expand...
I don't think I'd ever have the patience to do that either :p
Especially in my XT, it's just too much fun to drive, if you know what I mean :twisted: :rock:
But in saying that, I did manage to get 8.1lt/100km's once :raspberry: But don't know how though :)

Regards
Mr Turbo
 
I remember when my old V8 would average 15mpg- with a worst of 12. So things are definitely better these days as far as fuel economy are concerned. Miss the ol' girl sometimes...
 
Aussie gallons. MPG is like the English language. It was what I was first taught and I'm happy with what I know. Since the US, the UK, Australia and Europe are all on this forum, there is no standard anyway.
 
Your experience with the low fuel light is the same as mine with our Forester and Camry. Once the light comes on in the Forester, it stays on (however I doubt whether you will find it has 10L left - our 07 Forester comes on around the 50L mark and I have found it only has a useable 55.2L) but the Camry fades on and off over quite a few km's coming on early uphill and left corners.

As far as synthetic oil increasing economy, that's just what the manufacturers claim. I have only ever had the 5w-30 synthetic Subaru oil in mine up to the present 192,000km so have nothing to compare it with (except our V6 Camry is around 15% more economical).
 
Hume Hwy Sydney to Yass. As that takes you through the Southern Highlands it is uphill over that distance.
 
That 7.2L/100km ain't too shabby! That comes out to right at about 32.6 mpg (in us), which the best i've ever got in my 2.5L was 29mpg. I did have the wind to our backs, but we were also fully loaded down, inside & out with gear on our trip to Red River. Had we not been loaded down, i'm pretty positive we could have hit that.
All around here with the hills & constant stop signs to go through, i average around 24mpg.
 
hmm.... this is worrying, since my L series is getting about 11L/100km admittedly on larger diameter wheels/tyres but I do drive for economy with only 1 or 2 squirts for acceleration per tank... Is this normal?
and on the subject of oils, I know i have said this before in another thread, but I was told that Castrol Magnatec is a great oil for older motors (especially for quietening the EA82 ticking)
 
Species said:
hmm.... this is worrying, since my L series is getting about 11L/100km admittedly on larger diameter wheels/tyres but I do drive for economy with only 1 or 2 squirts for acceleration per tank... Is this normal?
and on the subject of oils, I know i have said this before in another thread, but I was told that Castrol Magnatec is a great oil for older motors (especially for quietening the EA82 ticking)
Click to expand...

Not sure about the oil but most likely it would help.

I would of thought you would get under 10l per 100km. Many km on the engine? if its around 300,000km then she might be starting to get abit tied.
 
I had the car fully loaded- rear seat down with camping gear of my own plus some from another group. And 53kg worth of skin and bone sitting next to me in the passenger seat, 22 litres of fuel in the jerry and 20kg of water to boot. Add all those last three together and the driver would still weigh more!
 
I consistently get around 7.2 - 7.4 on the highway, and around 8.8 - 9.0 in the city. 2.5 litre, NA engine with 0W-20 oil, 91 octane fuel and 225-17 tyres at 36psi. I drive at the speed limit, and never use cruise control.
 
0W20? New to me- never seen it before. I run 10W40 in the Forrie, 10W50 in the WRX. That would help economy, but it is below what Subaru recommend- especially in summer
 
Gidday Folks

I have updated my OP with a bit more info. Two edits.

I have been a bit busy the last couple of days.
Actually had to go to a client's and do some honest work today ...

Also had to pick up my 'new' ARB Magnum creeper winch from North Melbourne today. Will post some thoughts about this in another thread.

Thanks everyone for the thoughts, feedback etc.

When I have the 125,000 km service done (at around 114,500 kms), I will have Ross replace the diff and gearbox oil with fully synthetic as well. Seems like the way to go from what people have said here and elsewhere.
 
I can add to the fully synthetic theory, In one of my attempts to get better economy out of my territory before giving up and changing vehicles I started using Gulf Western fully synthetic oil. It actually worked a bit, I went from 16L/100km to 15L/100km. It was an amazing result although still not enough to save the car :lol:. I always put fully synthetic oil in the cars I like.
 
taza said:
Not sure about the oil but most likely it would help.

I would of thought you would get under 10l per 100km. Many km on the engine? if its around 300,000km then she might be starting to get abit tied.
Click to expand...


Engine has 190,000 km on the clock, original owner had it until around 180,000ks. The 200,000k service was done at 150,000k

I just ran through a can of UEC, new spark plugs, new air filter and an oil change
 
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