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2000 Outback 2.5L
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Discussion Starter #1
Heard on another forum that Castrol Synthetic oil is still mineral/dino oil, with synthetic additives, hence they call it synthetic. Story is that Mobil1 took them to court on this and lost, and since then Mobil1 has now switched to to mineral oil with "synthetic" additives. The thread had discussed that Amsoil is still a true synthetic.

Just wanted to see if anybody had something to add to this, for or against the claim.
 

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03 H6 OBW & 06 WRX Sportwagon
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In the world of gemstones with which I am somewhat familiar as a hobby faceter, the term synthetic means something very specific. Made from the same components by man in a laborarory instead of mother nature in the ground. Chemically, synthetic ruby is the same as natural ruby. In the lab they satrt with aluminum, chrome and oxygen to create it. While the analogy is not perfect, I doubt that ANY 'synthetic oil' starts with hydrogen and carbon. That is why there are 'classes' of syn oil. Also, I'm not sure the distinction is as important as the testing and real world results.
 

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MY99 3rd Gen Outback GX, 2004 Lexus RX330 Sport Luxury
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242 Posts
Well, Castrol "Syntec" is a group 3 semi synthetic. The only true "PAO" based synths that Castrol makes are the 0w30, 10w60 and 0w40 the latter two are not available in North America, the former is the infamous "German Castrol".

Group 4 PAOs and Group 5 Ester based synthetics are generally regarded as the "true" synthetics. As for Mobil 1 now being dino based, well there was a thread about it over at BITOG, and it was found to be incorrect. I have also e-mailed Mobil's tech Dept who assured me Mobil 1 is all PAO synthetic.

Regarding Castrol's claim that semi synths can be called synthetic, well plenty of people have negative opinions about Castrol's marketing. I know that in some parts of Europe, oil manufacturers are not allowed to call their products synthetic at all unless it's Group 4 / 5.
 

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'04 Colorado, '90 Legacy sedan
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137 Posts
To add to confusion to who has "true" synthetic base and additives is while researching a bit on syns is this:

there are different molecular make ups. Castrol has long molecules thus (AMSOIL) the claim reads they breakdown easier. Mobil1 and AMSOIL have shorter strands and claimed to be harder to breakdown.

I don't know, my previous Subies loved Castrol, Valvoline, and Pennzoil. My first a '78 BRAT cruised to 114k miles upon trading, my '83 had 112k and I sold it with 140k, my '96 OB had 102k and my '90 Legacy sedan 174k (30k are mine) All have achieved these no.s using dino based oils w/o using a single drop('90 and '96 got new seals). The '90 had two oil changes with syn oil, Walmart and Castrol with no obvious improvements in smoothness or economy. I have gone back to only dino. Regular changes will get my Subies down the road very well for now.

I may reconsider at a later date will see.

The debate rages on.

Todd
 

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Formerly 04 Outback 3.0R VDC, now 2011 Mitsubishi Pajero GLS DiD
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1,617 Posts
This is a quote to answer a FAQ on the Subaru Australia website:

What oil should I use in my Subaru? Can I use synthetic oils in my engine?

F.H.I. (Subaru Japan) have advised that they only require the engine oil used in Subaru vehicles to comply with the A.P.I. (American Petroleum Institute) classification for oil Quality and the S.A.E. (Society of Automotive Engineers) rating for oil viscosity as listed in your vehicle Owners Manual. F.H.I. do not differentiate between mineral and synthetic oils nor recommend a specific brand. Subaru Australia recommends staying with mineral engine oil until approximately 5000 to 6000kms to reduce the time and mileage taken to run in the engine. Synthetic oil generally produces less friction and therefore the engine run in time may be greater than mineral oil.
 

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SubaruOutback.org Founder
2018 Outback Limited 2.5L - 105,000+ miles
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5,122 Posts
From doing extensive reading over at BITOG I've found that Mobil 1 is the on mainstream true full synthectic oil. If proven wrong I'd still say it is the "most synthetic" oil I've read about. That being said I'll still stick with it over anything else :)
 

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Tokyo's between my toes
2001 Wintergreen Outback 5MT
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Ever run synth in a lawn mower?

I've used synth in a few mowers with good results. They seem to enjoy a lot more torque with the increased lubricity of the synth.

Plus, air-cooled engines can have some strange temperatures during service, so I like having the thermal stability of the synth. I like to let an engine idle down to a cooler temp before shutoff, just so it can blow cool air over itself for a while.

My father had a Toro push mower with a 3.5 hp Tecumseh engine. We ran Mobil 1 in it for 12 years, and that engine was still running strong when the mower was retired to the country.
 

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Outback onsight...
'03outback, '98 forester S lifted m/t's, 4eat, lsd
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1,264 Posts
synthetic and or blends superior!

As a mechanic I have built and run many engines/drivetrains using synthetic/semi-syn/ petrol based oils.
I personally have seen engines perform better under high stress/ high rpm/heat conditions. Results were higher sustained oil pressure, less contamination and breakdown. Drivetrains most people forget about changing .
While working at Freightliner (heavy trucks) we had long hual drivers from across the country who ran synthetic in their drivetrains that were getting 2 mpg more fuel mileage! that's a huge savings when your drivng 150,000 miles a year!

I personally have run synthetics since 1990 in all my vehicles from four to eight cylinders and drivetrains. The initial investment is high by you'll reap your rewards with less breakdowns and overall maintaince costs. All sythetic/semi syn oils meet or exceed warranty requirements too. Remember to change oils on regular maintainece intervals and increasing changes under extreme conditions such as racing/towing/off road/heat/cold/turbo-supercharged/forced induction devices like roots type blower/nitros oxide. I don't recommend any particular brand since the market is flooded with propaganda saying theirs is best. You'd have to do some scientific reseach from a non biased testers. I just go by trial and error method & basing my conclusions on th the outcome of my own testing .
 

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MY04 Outback 3.0
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75 Posts
Re: synthetic and or blends superior!

scooby said:


I personally have run synthetics since 1990 in all my vehicles from four to eight cylinders and drivetrains. The initial investment is high by you'll reap your rewards with less breakdowns and overall maintaince costs. All sythetic/semi syn oils meet or exceed warranty requirements too. Remember to change oils on regular maintainece intervals and increasing changes under extreme conditions such as racing/towing/off road/heat/cold/turbo-supercharged/forced induction devices like roots type blower/nitros oxide. I don't recommend any particular brand since the market is flooded with propaganda saying theirs is best. You'd have to do some scientific reseach from a non biased testers. I just go by trial and error method & basing my conclusions on th the outcome of my own testing .
So Scooby what brand do you use?
:confused:
 

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Outback onsight...
'03outback, '98 forester S lifted m/t's, 4eat, lsd
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1,264 Posts
synthetic oils

I use a Valvoline(semi-syn) durablend 5-30w for engine (for cost reasons $1.99a qt. is better than $3.99 a qt.for full syn.) I personally change my engine oil at 4,000miles(mostly highway miles).
I use Valvoline full synthetic 75-90w in the differentials. For the trans . I use full synthetic Castrol Syntec ATF (DEX Mercon type 3)(mainly for availablity) .
I have used castrol full synthetic syntec in engines with great results . I don't recommend any particular brand since most are comparable. I've found that if you shop around look for the most common one available . This will save alot of headaches when you need oil. Our shop uses Amsoil/Valvoline/Castrol mostly due to distributorship or cost.:p
 
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