Oil in the intake...

[Bruticus]

Hey guys,
When I had my $400.00 tune up about a month ago, my mechanic (don't fear I work on cars too, just don't have tons of time or a garage...) told me he found oil gunked up in my intake, he said that is what fouled my plugs. He told me he cleaned it and put new autolites in along with a new intake gasket. He recommended that I use 5w-20 Motorcraft oil, which I did change (I was using 5w-30 valvoline durablend). Any helpful thoughts would be appreciated as to why I had oil in my intake, is this a common problem, and what can I do about it.
Thanks

 

[LJRuddy]

Every intake with some amount of miles is going to have oil in it... It has to do with the vacuum hoses that vent the crank and valve covers... Seems to me that, unless you noticed a substantial loss of oil between oil changes, i dont see how the oil in the intake could affect the spark plugs. Even then, i dont see how that would cause the problem he told you about. What i am trying to say is if oil had messed up the plugs, i doubt it would be from the intake... Possibly bad valve seals or something like that? But then again, you dont have smoke on start up do ya?

 

[Mr Anonymous]

The sludge in the intake is common, and is a result of the PCV, EVAP, and EGR systems. We recommend cleaning the intake every 50K miles or so.

If you like the car, get that 5W20 the **** outta there and put in 5W30!

 

[Bruticus]

Thanks...

Every intake with some amount of miles is going to have oil in it... It has to do with the vacuum hoses that vent the crank and valve covers... Seems to me that, unless you noticed a substantial loss of oil between oil changes, i dont see how the oil in the intake could affect the spark plugs. Even then, i dont see how that would cause the problem he told you about. What i am trying to say is if oil had messed up the plugs, i doubt it would be from the intake... Possibly bad valve seals or something like that? But then again, you dont have smoke on start up do ya?

Well I have no smoke on startup, not that the oil would not burn up in the cats...I will change the oil next change, winter and all. The oil that he found had apparently been building up for sometime.

 

[Mr Anonymous]

99% of the motoring public has the same sludge building up in their intake manifolds right now. Chances are, very little oil vapor is actually making into the cylinders, if a lot was you'd have frequent knocking and resulting KR.

Now, if you do have frequent knocking, or the oil was pooled in a liquid form in the surge tank, then you could have a PCV problem. An OE PCV valve (there is NO suitable aftermarket replacement) is under $10. Depending on how deep you want to get into the car, you can install a PCV catch can or filtering setup to reduce the amount of oil entering the intake tract, as well as have the EGR system disabled in the programming to reduce the carbon and the baking effect.

Ok, I don't know if I can stress this any more strongly: 7 quarts of 5W30 and an FL400S filter can be had for under $15 at Wal-Mart. Seems a lot cheaper than replacing a motor that has spun a bearing with oil that is too thin at temperature to properly lubricate the motor. Doesn't matter what time of year it is, 20 weight oil is inappropriate in these motors. When seasons change, you might consider changing the cold weight (IE going from a 5W30 in winter to a 10W30 in summer), but you never want to go to an oil that is thinner than 30 weight at temperature. With a high-quality synthetic you can go the other direction a bit, say to 5W40, but right now every minute you run that car with 5W20 you're taking an even bigger risk than the unwelded cams!

 

[jedhead]

If you get your intake extrude honed, the runners will keep clean. The oil from the PVC doesn't seem to stick to the finish left by extrude honing.

Bob

 

[SHOZ123]

It's not so much of a problem to get the oil in the intake tubes and surge tank as it is for the oil to carbonize on the butterflies. This will eventually cause the IRMC to fail due to the strain produced on the cable to open the butterflies or codes you will get because it cannot shut them.

The problem on the V8 is greater than the V6 because of the location of the butterflies. On the V6 they are between the tubes and surge tanks. On the V8 they are right above the valves in the Lower Intake Manifold (LIM) and subjected to much greater heat.

Of course a condesation type device in the PCV line prior to the surge tank to trap the blowby will eliminate the problem.

 

[NoSlo]

I guess the better question is..What the heck did he 'tune-up' for $400?? There isn't much to do to the engine except the 60K service and weld some cams if it doesn't have problems. I think a lot of customers have been programmed to 'tune-up' a car, from older cars that needed timing adjustment, points, distributor cap and rotor, short life spark plug replacement, accessory v-belts, and **** jobs, and there are still shops that will do a 'tune-up' for you when you ask for one, even when there is nothing to do.

One thing, however, that should be on a service interval but most people neglect is the transmission fluid - every 20k to 30k (or fill it with $100 of AMSOIL ATF and bump that up to 50k). Flushing out the torque converter, dropping the pan, and replacing the filter using the flush procedures you can find on the forum can drastically extend the life of the transmission by removing friction material particles that would otherwise continue to circulate and wear the tranny.

The spark plugs should have been Motorcraft and the oil should not have been 5w-20! The retroactive TSB by Ford that authorized the use of 5w-20 on older cars does not include the SHO. The '5' can be justified in cold weather for start-up wear protection, but the '20' weight is the higher viscosity for hot operation. The engine will still warm up to 185+ degrees regardless of the outside temperature, and the '20' is too thin.
The only reason for 5w-20 to exist at all is to improve fuel efficiency for the entire production line of cars by a fraction of a percent so Detroit can crank out more SUVs and still meet CAFE requirements.

Did you at least get new oxygen sensors or spark plug wires out of it? Did the computer have stored misfire codes that might have been from fouled plugs?

 

[SHOZ123]

I'm sure the $400 was mostly labor as the uninitiated on the V8 SHO will take some time disassembling the intake. What with the EGR, DPFE, tank straps and that pesky ground wire. Cleaning the runners and surge tank also take some time.

Like Chris said the oil is normal and if left on it's own will turn to carbon. But the oil definitely should not be 5w20 and synthetic will reduce the blowby a bit. The blowby can also be reduced by treating with Auto-RX which will clean the accumulated carbon from the oil control and compression rings on the pistons. This will allow better compression and cleaner running.

 

[Bruticus]

Yes the computer had a host of misfire codes, plug #8 and some problems with the IMC. I will keep the 5w-20 (which is semi synthetic) in until March when the weather warms up here in Ohio. I don't drive the car that often (I have a take home cruiser), but I will switch back to a 5w-30 or a 10w-30 durablend. They did spend some time cleaning the intake and such, the mechanics are good, but they have never worked on a v-8 SHO before. Thanks for your input.

 

[SHOZ123]

Tic Toc Tic Toc

:corn:

 

[lancSHO]

NoSlo, the V8 SHO's don't have spark plug wires.