What weight Synthetic to use in an oil burning engine

Messages
10
Location
T.O
Hey everyone. I have been surfing the board for some time now and thought I would finally post a question.. I own a 91 Prelude /W 77k miles on it... the car has been on dyno oil since day one ususally using 5W-30 castrol GTX/Honda dyno juice. I have been switching between 5w-10W in the summer and see a reduction in oil loose. I currently use about 1 liter of oil for every 2500kms of driving (5w) I loose less when I run 10W. I want to try M1 supersynth for my next change to see how the car runs and how much it will burn.. (Im curious what weight I should use 10w-30? 0W-40? ectect.) Burning oil is a common problem on my engine B21A1 cause by a long bore/stroke ratio and piston blowby (the rings honda used were apparently very revoutionary at the time... they dont use them any more... [Smile] Anyways any help would be great [Smile] Thanks
 

Ed

Messages
135
Location
Southern California
Why bother to go to the expense of useing synthetic with an engine that has high consumption.? If you're like me you are probably driven by curiosity. Synthetic certainly won't hurt anything but it may even disappear faster than dino. I would recommend starting off with 10W-30 and add 15W-50 as make up oil as the 10W-30 is consumed. I would think that any 5W or 0W would be unsuitable for any engine that has oil consumpton problems. Castrol makes a 15W-40 semisynthetic (Marketed as a "truck oil") and would probably be ideal for your situation. [Cheers!]
 

Falcon147

Thread starter
Messages
10
Location
T.O
Yup its the pison rings that are the problem... In all honsetly im not only curious about using the synthetic... but I also want to give my engine a good cleaning, Im hoping that the additional cleaners in a synth oil will clean up some of the carbon build up.. I personally wont use a engine cleaner like Auto-RX just because my engine is still young though it burns like an old man [Smile] When im at the point of no return I would use an additive like cleaner:)
 
Messages
6,388
Location
Washington St.
Your engine is 12 years old with 77,000 miles. Were those miles from many short trips? That ages and wears an engine, maybe more an a 12 year old engine with many more miles from easy highway driving. The Auto-Rx is said to have a money back guarantee...all you're out is the shipping. In any case it does no harm. There have been success stories posted here. Ken
 
Messages
154
Location
Chicago
Stopped by the dealer today for a visit (mechanic friends) and a customer brought in a new car with 15,000 miles for the first oil change. Needless to say the Castrol 5-30 turned into molasses. They were talking B-G flushes when I left.
 

Falcon147

Thread starter
Messages
10
Location
T.O
Actually most of its life has been on the highway.. about 25 minute trips back and forth to work.. [Smile]
 
Messages
605
Location
Mississauga, Ontario
What about this:? I've heard that initially the synthetic will clean the seals and the consumption could increase but with time the esters will swell the seals and reduce/eliminate consumption? Any validity to this?
 
Messages
6,388
Location
Washington St.
_Lude, What you're saying is kind'a right, but his problem isn't leaky seals, it's poor seal of the oil control ring (which has nothing to do with blowby, that's the compression rings). Falcon, I see no point burning expensive synthetic oil. In your case, I'd try a 10W-40 or an API-SL 15W-40. Could the oil control rings be stuck in their ring grooves with baked-on carbon? If so, a treatment with Auto-Rx or Schaeffer's Neutra would help free up the rings, allow them to do their job, and reduce the oil burning. Also use Neutra or other good combustion chamber cleaner to remove the burned oil residue. Ken
 
Messages
10
Location
Toronto, Canada
I've got the same 91 Prelude with a B21A1 engine that has 175,000 miles on it. It uses about 1 quart every 1,000 miles. I've had Castrol Syntec 5W50 in there during the heat of summer and Mobil 1 5w30 and 10w30 during the Canadian winter. The consumption seems to be about the same. I've noticed that when I do a lot of highway driving at 70-80 mph I really go through the oil, but I think that's expected. I'm sticking with synthetic oils because I want the engine to get to 300,000 miles before I rebuild it. Good synthetic oil is cheaper than a rebuilt or used engine. I've recently started using Amsoil 10w40 and go a little thicker (20w50) during the summer. An engine flush may be in the cards this spring. [ March 05, 2003, 03:54 PM: Message edited by: rimmer1 ]
 
Messages
1,357
Location
California, USA
Where did this myth start that synthetics "clean" an engine? It's like the OWT that ATF has extra detergents, not true. If you want an extra detergent/dispersant oil, use a 15W-40 grade HD oil. It will reduce your oil consumption by being slightly thicker at operating temperature and by having a higher flash point. These oils are also formulated to keep the rings from sticking due to deposits. Chevron Delo 400 is my favorite, but Shell Rotella T and Mobil Delvac are also excellent.
 

Patman

Staff member
Messages
21,989
Location
Oakville, Ontario
quote:
Originally posted by Jimbo: Where did this myth start that synthetics "clean" an engine? It's like the OWT that ATF has extra detergents, not true.
It's not really a myth though. The esters in many synthetic oils will clean an engine. That's why oxidation is so high on the first run people do with Redline or Amsoil. After that first run the engine is cleaner and the oxidation settles down.
 

Falcon147

Thread starter
Messages
10
Location
T.O
Well I just really want to cut down on engine wear, I will probabaly try 10W30 M1 and Add 15W50 as the make up oil to see how I fair.. what do you guys think? maybe, what about the lenght between oil changes with synth... 6000k miles?
 

Patman

Staff member
Messages
21,989
Location
Oakville, Ontario
quote:
Originally posted by Falcon147: Well I just really want to cut down on engine wear, I will probabaly try 10W30 M1 and Add 15W50 as the make up oil to see how I fair.. what do you guys think? maybe, what about the lenght between oil changes with synth... 6000k miles?
In most engines, I believe 6000 miles (10,000km) is a totally safe interval with synthetic oil. Some Toyota V6s can't handle that long though, they turn the oil into sludge before that point.
 
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