i always ran synthetic in my 86, but it had a brand new engine, is it safe to run synthetic in my 95 3.4 after 79000 miles? My dad says i might start to burn oil. i know thats the way it used to be when synthetics first came out. is it still bad to switch to synthetic these days?


-Bruce

 

Well a synthetic oil molecule is smaller than a conventional oil molecule. If your seals have worn out over the years, you could get engine leaks. If your rings are worn to hell, you could burn a bit. If your valve stem seals are shot, you'll get smoke on startup. It all depends on how beat up the seals are.

I'd say give it a shot; if you burn and leak oil, go back to the dino stuff! I wouldn't try synthetic in my motor; it's way too old to keep the stuff in.

 

I have a synthetic blend and I have noticed all of what tomp said. If switching back to dino oil will fix some of this, I should do it! Does anyone know if this will hurt anything?

 

Just make sure to change oil more frequently than synthetic... they say synthetic is good for 7500 mi. but I wouldn't go more than 4000 and I try to get oil changed before the 3000 mi mark. Of course the 3000 mi. oil change is known by everybody.

 

What about the Syntec Blend stuff, i use the Castrol brand, engine has 213,000 miles and noticed a better difference from regulay castrol.

 

When I bought my car I did an imediate oil change to synthetic. Full synthetic. That was at roughly 68K miles. No troubles. Now over 40K miles later its just now starting to puff alittle at start up. No biggie, its getting ready to get rebuilt anyway.
But I will say I noticed a difference in EVERY vehicle I owned when I switched to synthetic. Easier starts, uses less oil, better milage. the list goes on.

AND I change my oil about every 7K miles, or every 5 months. I did change it more frequently after I first switched to get all the "dino Oil" as someone put it outta the engine. I did the last change at about 6800 miles and the oil was still slick as snot(a little sooty) but no friction. Not bad considering the oil changes are not only about the same cost roughly 20 bucks and last 3 times as long over conventional.

After the rebuild I am going to get that Amsoil soot filter thing... try to keep the oil nice and clear...

 

The first thing I did was change to the synthetic oil for higher mileage engines and I did notice the change. It does not even burn a drop.

 

thanks for the info guys

 

try to change oil every 50 hrs of operation. the 3mo/3,000 mle rule does not compensate for engine idle time. I f you have a used/rebuilt motor, put one of those hourmeters on.

 

I have also heard the myth that synthetic oil can be changed less frequently then traditional oil. NOT TRUE! Synthetic oil breaks down just as fast as the old stuff. it may still run better after 6k and 7k miles that you guys are talking about going, but it is still broken down by then more tehn likely. The opnly reason ther mileage etc. is still good is simply the smaller molecules. I try to change my oil every 4k miles, using traditional oil, the same will be true if I ewver switch to synthetic. Just wanted to pass that tip along............

 

I have always head that synthetic does not break down as easy

 

After much debating, considering I had 145,000 miles, I switched to synthetic. I was kinda worried about burning oil, but haven't had any problems. No smoke at all. Leaks a little more though.