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Interesting info on synthetic oil recommendation

2

Comments

  • aathertonaatherton Posts: 617
    edited September 2010
    Yes, the DOHC turbo and diesel engines have semi-closed cylinder decks, which must be sand cast.

    They cannot be die cast, like the open deck decks of the SOHC NA engines, because the cast webs holding the cylinder tops prevent withdrawal of a die.

    The sand-cast semi-closed decks do not place stress on the head gaskets, which is why this design is being used for the new NA engines.

    You and the OP perhaps think that some sand remains in the sand-cast engines. And the OP may believe that all engines make metal shavings as they break in. These would be misconceptions.

    All engines are thoroughly cleaned of casting and machining contaminants before assembly. And break-in only produces microscopically fine particles polished off the rings and cylinder walls, too small to be captured by filters. This material is captured and bonded to the detergent additives in the oil. And there is very little of it.
  • saedavesaedave Chicago, ILPosts: 680
    The sand-cast semi-closed decks do not place stress on the head gaskets, which is why this design is being used for the new NA engines.

    But where has Subaru revealed "semi-closed deck" for the 2011 NA Forester engine? We all would be pleased with that design and it was one of several reasons I bought a 2010 XT for my mainly slow city driving...as well as the better match of lower speed engine torque to the 4-speed auto trans.

    Will the potential increase in manufacturing cost necessarily raise prices of all 4 cylinder models? If warranty costs have been high enough with the die cast blocks, an increase may not be necessary to maintain profit margins.
  • aathertonaatherton Posts: 617
    edited September 2010
    "... where has Subaru revealed "semi-closed deck" for the 2011 NA Forester engine?"

    They have not. You must infer it. This says the turbo and the diesel use the DOHC semi-closed deck which saves the head gaskets:

    "The BOXER DIESEL adopts a semi-closed cylinder block deck to improve the rigidity around the head gaskets, following the precedent of the semi-closed type used in the Subaru EJ20 turbocharged gasoline engine."
    http://www.boxerdiesel.com/engineering/en/03.html

    Then these say the 2011 NA engine is also DOHC:

    "... for the 2011 Forester... Also of note is the switch from SOHC to DOHC..."
    http://www.autoguide.com/auto-news/2010/07/2011-subaru-forester-gets-new-base-en- - - gine-improved-fuel-economy.html

    "... for 2011, the Subaru Forester gets a new volume engine... double overhead cams (vs. a single cam previously)..."
    http://www.autoguide.com/auto-news/2010/07/2011-subaru-forester-gets-new-base-en- - - gine-improved-fuel-economy.html

    You have to assume that Subaru, in making the DOHC engine standard across the line, will use the same semi-closed deck for all of them. In a month, you can go see the new engine on the dealer lots.

    The new engine has two significant improvements:
    1. For all models, replaces the breakable timing belt that had to be changed every 100K, with a permanent timing chain.
    2. For the NA models, it replaces the open deck SOHC engine with the semi-closed deck DOHC engine that has unlimited head gasket life.
  • saedavesaedave Chicago, ILPosts: 680
    You have to assume that Subaru, in making the DOHC engine standard across the line, will use the same semi-closed deck for all of them

    You are using THE instead of A DOHC engine. I believe the XT engine was described as unchanged for 2011.

    I hope you are correct that the semi-closed deck block is used in the NA engine.
  • aathertonaatherton Posts: 617
    edited September 2010
    I meant that Subaru is using the same block design for all the engines -- the turbo,the diesel and now the naturally aspirated. For the turbo and diesel, this would not be a change. Only for the NA. Or, are you saying the DOHC turbo engine will stay with the belt drive while the DOHC NA engine gets the chain drive?

    On the decks, I suppose you could read the sources posted and come to the opposite conclusion - that for 2011 Subaru has designed a new open deck block for the DOHC motor, for use in the NA models only. In spite of what they said that they know about the effect of open decks on head gaskets.
  • saedavesaedave Chicago, ILPosts: 680
    Or, are you saying the DOHC turbo engine will stay with the belt drive while the DOHC NA engine gets the chain drive

    That is the implication of the "unchanged" description. It would also mean no recertification cost for the XT right now, possibly a consideration. It also suggests to me that a next iteration of the XT engine might have the turbo below like the diesel. The mention of 2.0 liter to 2.5 liter displacements may also be a clue. I wonder what output a 2 liter turbo GASOLINE version of the diesel would have. I presume it would be tuned more for economy than the Japanese market turbos.
  • aathertonaatherton Posts: 617
    edited September 2010
    ...that is the implication of the "unchanged" description. It would also mean no recertification cost for the XT..."

    Some things are unchanged.

    For the turbo, the engine has no changes requiring recertification. A change from belt to chain drive would not require recertification.

    For the NA, the 2.5L has no changes to displacement or power.
    But the NA does get DOHC and chain drive, for which it is called a new engine.
  • saedavesaedave Chicago, ILPosts: 680
    For the NA, the 2.5L has no changes to displacement or power

    Not what I read:
    1) more displacement
    2) max torque at lower rpm
  • aathertonaatherton Posts: 617
    edited September 2010
    "For the NA, the 2.5L has no changes to displacement or power.
    But the NA does get DOHC and chain drive, for which it is called a new engine."


    "... Not what I read:
    1) more displacement
    2) max torque at lower rpm"


    We are both reading the same article that says:
    "... slightly larger displacement (2,498cc vs. 2,457cc)... horsepower remains at 170... Torque edges up from 170 at 4,400 rpm to 174 at 4,100 rpm..."
    http://blogs.insideline.com/straightline/2010/07/2011-subaru-forester-gets-a-new- -base-engine.html

    But I did not consider that increases of 41 cc and 4 ft-lbs were significant enough to mention as design changes that would call it a new engine.

    The NA engine is called new not because of those insignificant changes in displacement and torque, but because of the DOHC heads and the chain-driven cams.
  • "... In a month, you can go see the new engine on the dealer lots."
    And here's a photo now;
    http://response.jp/imgs/zoom/249397.jpg
    Less expensive industry standard plastic intake runners. One serpentine belt for all the pumps and accessories. Cam chains buried deep in front cover. Cam ends with their hydraulic and electronic controls protruding out the front.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,281
    Hmm, yeah - that looks a LOT different than the current SOHC or the DOHC of years past. Even the dipstick is far removed. I can't say I would miss the timing belt, though!
  • It also has a top-mounted oil filter, next to the filler tube. No more reaching up through the hot exhaust shields and spilling oil on them.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,281
    edited September 2010
    Oh, is that what that is? I'm no fan of the hot exhaust (tried it once), but it is easily solved with the help of an oil filter socket (about $7). I don't like the concept of a top-mounted filter (sounds messy and would be problematic to pre-fill), but if they set it up properly, it might just work out and would be really nice if it did!
  • aathertonaatherton Posts: 617
    edited September 2010
    "... I'm no fan of the hot exhaust... but it is easily solved with the help of an oil filter socket... I don't like the concept of a top-mounted filter (sounds messy and would be problematic to pre-fill)..."

    I have done my Forester oil changes at 3,750 miles for 24,000 miles. The gusher of oil from the oversize plug, and the filter location, make it the hardest car I have ever had.

    The socket only enables the filter to be loosened. If unscrewed with the socket, oil will go everywhere. After loosening the filter, it can be removed rather cleanly by careful use of a 12 oz. paper coffee cup. The technique would complicate this post.

    The 2011 top mounted filter is contained in a cup. Oil from the removed filter drains back down into the engine.

    I have never pre-filled a filter in 50 years. A nice touch but not called for by mfrs or done by dealers or oil change shops. Pre-filling is unnecessary because the residual oil in the pump, and the oil films in the engine, last for minutes, while the oil pump refills the new filter in seconds.
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,281
    The 2011 top mounted filter is contained in a cup. Oil from the removed filter drains back down into the engine.

    That should work pretty well, then. Do you know if this engine uses the same filter as previous? From the photo, it looks like it may be a shorter/wider unit and would hopefully include an anti-drainback valve.
  • aathertonaatherton Posts: 617
    edited September 2010
    I have no idea what kind of filter is uses. It would be nice if it used a regular type of filter that screwed into a regular mounting plate at the bottom. But with that cup, it might be some special OEM filter that screwed into the cup itself. Or even a canister filter contained in the cup.

    The Saturn 2.2L Ecotech engine has had a top mounted filter for years, but I don't know it's details.
  • ateixeiraateixeira Posts: 72,587
    I love that cup idea, and the top-mounted filter. This will cut oil change time in half.

    It's funny, I was just complaining to rsholland about how the filter was surrounded by hot exhaust on our 2009 model (that was not the case on my 1998 DOHC). Plus the dealer overtightened the filter and I could not get it off even with the oil filter socket wes recommends.

    So I went out and got a huge adjustable wrench that bites down and reaches up in to that cavity and got it loose. Without that tool I could not have removed it.

    GoodYear auto service overtightened the filter on my Sienna, also, so I think I'm done letting others change our oil. 2 bad experiences are enough.

    Plastic intake runners should put less weight at the top of the engine. I was always fascinated at how solid the old metal ones were, but it was probably overkill.
  • ateixeiraateixeira Posts: 72,587
    That's what it's called. Mine's huge and strong enough to crush the filter and long enough to reach in there and get it out! Here's a pic:

    http://www.benmeadows.com/images/xl/10L-Straight-Jaw-Pliers-BEN-_i_LBM42760Z.jpg-

    I actually got it for my Sienna, to remove a canister-type oil filter that was overtightened. Every handy man should have one of these.

    image
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,281
    edited September 2010
    Yeah, I have a couple of those and they can definitely come in handy in a pinch. Since we're on the topic of oil filters, I had to use my larger one (probably about 15-16 inches long) to pull both of the oil filters off the Ford engines I was finishing up this weekend.

    I literally would not have been able to remove them without this tool. I even had the engines out of the vehicles at the time!
  • ateixeiraateixeira Posts: 72,587
    Interesting.

    On my Toyota, I gave up (prior to having that tool) and made the folks who overtightened it remove the filter for me. They had to drain the oil so they refilled it for free (I provided the filter element).

    No other tool could remove it, but this one will.
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