Hello Everyone,
I have always used DINO oil (regular oil) in my car since I have owned it (roughly a year). Upon startup, hot or cold, I never saw any evidence (not even a little) of the dreaded blue smoke puff at startup.

A friend finally convinced me to go synthetic and now when I start the car in the morning I am greeted with a huge puff of blue smoke. Also if it sits after driving for 3-4 hours, I get a little puff.

Does this happen with everyone who switches? Car has 73K miles and all original. Nothing else has been done to the car. I am convinced if I go back to dino oil it will stop. Always used 10W-30 oil, either synthetic or regular.

Also, am I causing harm with this blue smoke? not sure what to do now..

Thanks

 

Blue smoke on startup after sitting a while is usually valve seals. can't tell you if going back to dino oil will stop it or not or even if the synthetic caused it, I would guess maybe the swap pointed out a problem sooner. With 75K they were more than likely worn already, relatively common issue on SBC. Valve seals are a fairly easy fix as long as you the right stuff not real expensive if you do them yourself. It probably will not hurt the motor other than using up the plugs before their normal lifetime and having to add oil more often. I have seen some run for years without a problem. I personally would replave them just so I wouldn't have to spend money on oil and plugs, besides any puff of smoke from anywhere on my car bugs me.

 

Synthetic oil cleaned away the nasty deposts left behind from years of conventional oil which were clinging to your worn valve seals and keeping the oil from running down onto the valve.

 

Worn valve seals sounds right on. Not to worry, you may have to clean or replace your plugs more often and you may use slightly more oil but it should`nt do any damage. I am not sure about deposits on your pistons. Another will have to answer that. Next time you need to replace your valve cover gaskets or have another reason to pull your valve covers, it would be a good time to replace the valve seals. It`s not a hard job. After you replace them, if you have been running hot, this would also be a good time to get your cooling system in order.

 

I was talked into the same scenario at 98K miles and had the same thing happen. No clouds of smoke before, and then with the synthetic I've gotten puffs on start up. I changed back to conventional oil and the smoking is still there but not as bad. I've come to the same conclusions as to the valve seals diagnosis above.

Now, back to synthetics, I'm a firm believer in them for low mileage or new engine usage until this summer. In my '03 Silverado I've used it since new and couldn't be happier. But in my '77 Can am with a fresh rebuilt 400 with just over 250 miles of break-in on it, I switched to Mobil one and immediately stated seeing excessive oil consumption. Like a half a quart in 100 miles and no signs of leaking and I was oil fouling spark plugs. When I consulted the machine shop he said switch back to conventional oil and see what happens. So I did and the fouling quit and my oil level hasn't changed in the last 200 miles so I suspect it was from the synthetic.

I'm no petroleum engineer but maybe the make up of the synthetic molecules is somehow allowing it to get by the oil rings and into the combustion chamber and maybe it's just with older, flat tappet engines that it does this but until I get thousands of miles on the Can am's engine I'm not going back to synthetics.
On my truck, I'll still use it.

 

The synthetic is a lot "slicker" and will find the weeknesses. Going by what I have heard and read about synthetic in a fresh motor, I have heard not to switch till after 500+ miles and follow the right break in procedure.

 

I agree 100% with what Apeiron said about the seals. conventional oil has a bad habit of leaving deposits due to its inability to deal with the excess heat with causes it to "bake" and break down into what ends up as a deposit and this sludge usually accumulates anywhere oil tends to seep causing the seepage to slow or stop. Now when you think about valve guides and seals, the guides are designed to maintain a certain amount of seepage to allow for lubrication, the seals must allow for that miniscule seepage which unfortunately allows stuff in the oil to deposit there and actually hides a problem that develops down the road from the oil starved seal wearing out. Then when you go and change to a synthetic oil, which is far superior to conventional, it immediately attacks any build ups anywhere that oil gets to and once that build up on the seals/guides is broken down and washed away, now you have a problem that shows up which was there all along.

Now with new engines, you should never break-in with synthetics. you should run a special synthetic breakin oil, or use conventional for the first 500-1000 miles, and then switch to synthetics.

Its a common myth that synthetics will leak easier than conventional oil, but thats crap. Fact of the matter is that a 5W30 synthetic is exactly the same thickness as a 5W30 conventional, so they are both equally capable of leaking through the same problem and one is not thinner or thicker than the other as some like to think.

I would also recomend synthetics to everyone, but only on a sound engine with no leaks that was properly broke in.

 

18 year old SBC + petroleum based oil + 73k miles = hardened, cracked valve stem seals.

There are a lot of misunderstandings about synthetics, #1 is that they ruin old engines - no, they just clean them up. Right up there is "synthetics is synthetics" - Not! Add to that, don't break in a new engine with synthetic - many, many cars are factory filled with synthetic now - that "rule" only applies to engines with flat tappet cams. And "synthetics are thinner" (or "thicker") - hgffrank is right, although only at the specified temperatures for the viscosity rating applied.

Exactly what "synthetic" did you put in the engine?

 

I used mobil 1. I think I made a mistake doing this because I am getting alot of blow out not when prior I had absolutely no problems with the engine, smoke, etc.

Oh well..live and learn..and I guess valve seals are next...

 

Change the valve stem seals, change the now-contaminated oil.

Mobil 1 is a better choice than any petroleum based engine oil out there. It isn't my personal choice, but certainly better than anything that starts with a "P".

 

Synthetic oils in a used engine tend to find the spots where dino can't get out, therefore causing a leak.

Synthetic oils resist breakdown from excessive heat. That means your oil change intervals can be extended. Also synthetics do a better job of keeping your multi-viscosity range/rating (like a 10-40 dino oil will quickly turn into 5-30).

When I rebuilt the engine on my old Intrepid, I used 5-50 full synthetic...through blackstone laboratories and $30 to test my oil, I was able to confidently go 5,000 miles between oil changes (also using synthetic oil filters, ex. tough guard), they were actually telling me to keep going, but I had already changed the oil.

 

Sealed Power doesn't recommend breaking in a new engine with synthetic with their rings.

 

You must utilize the correct machine finish on engine parts in order to begin an engines life with synthetic, like Corvettes.

 

Mobil has a pretty good Info page on synthetic oil myths .

They state it's OK to break in a car with Synthetic oil and list all the cars that come from the factory with synthetic oil in the crankcase. I have three vehicles sitting in my garage (90, 98 and 2003) and I have the owner's manual for them. In the 'lubrication' section NONE of them say not to use synthetic.

FWIW, I started using Valvoline full synthetic in my GTA at 70K miles and have put on another 20K over the years with no leaks or other problems.

 

Another myth.

 

Hey Everyone,
Thanks for the replies...well today I have started the car at least 5 times and not once a puff of smoke! I cannot explain why it did it the 4 times yesterday (and it wasnt from oil on exhaust pipes, etc.). Possibly the oil filter did something with whatever was loosened? (I got a great WIX one).

Either way I am feeling much better. It seems to be running cooler, it seems faster or maybe it is my imagination?

Either way..no more smoke = happiness for me.

Thanks...

 

Ya, probably (I haven't tested it), I just read it in many different posts before when I was researching something about synthetics on different forums...no sarcasm, myths are all over the place

 

Always break inn with an engine mineral oil and cam lube if it is a flatcam, rollercams whitout camlube and the oil the ring or pistonmakers recomend.