jim beam wrote:
> 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.

Read my reply again: "One swells the valve seals; if you did the
seal replacement right then you can rule that out." Ah, usenet...