On 09/13/2009 03:39 AM, Leftie wrote:
> jim beam wrote:
>> Leftie wrote:
>>> Elle wrote:
>>>> On Sep 11, 8:41 pm, jim beam <m...@privacy.net> wrote:
>>>>> here's something to consider - an old "trick of the trade" is to use
>>>>> some of that crappy "stop oil consumption" additive when a dealer
>>>>> sells
>>>>> a known dud car. it works fine for a while, then, once a few months
>>>>> have gone by and it's no longer a quick come-back, it breaks down and
>>>>> oil consumption rises again.
>>>>
>>>> I was not aware that such additives existed but I can certainly
>>>> believe this is what happened and I got sold a car with a way worn
>>>> engine. This may be a lesson of used car buying, even with a clean
>>>> title and second owner status. Worst case I guess I may live with the
>>>> oil consumption and then at some point chase down an engine to swap
>>>> in.
>>>>
>>>> I will keep this thread updated.
>>>
>>>
>>> There are two types of additives to lower oil consumption. One swells
>>> the valve seals; if you did the seal replacement right then you can
>>> rule that out. The other kind thickens the oil to slow blow-by past
>>> the rings. That would have been removed not long after the oil
>>> change. You can do a simple test to see if it's worn rings: pull all
>>> the plugs and the air filter, then run a compression test with the
>>> throttle wide open. If you have worn rings OR valves, the compression
>>> will be low. Then squirt about a tablespoon of higher-weight oil like
>>> SAE 80 or 90 into each cylinder and repeat the test. If the
>>> compression shoots up, you have worn rings. It if only rises slightly
>>> or not at all it's worn valves.
>>
>> valves don't affect oil consumption.
>
>
> Valve seals do, however. I was assuming that worn valves would be leaky
> as well, but maybe not.

read the thread - they've been replaced already.