What's a "federal" vehicle?

Look on the id plate on your radiator support. See all the 3 digit numbers? Look for 491 or 494, you will have one of them. 491 is Fed version, 494 is Cal version. Spark plugs last a lot longer when you use 100% unleaded gas.

Ie, they're all Federal versions now as leaded gas is no ore.

/* Richard Marlin wrote: every 30k miles, except for federal vehicles, [where] you should change them every 15k miles

Isn't that backwards? {Do,Did} Federal vehicles use leaded gas?

No, it is correct. Fed cars did use leaded gas, leaded gas make spark plugs wear out quicker, so Fed cars require spark plugs every 15K. Didn't the UK recently, i.e.within 2 years ago, finally switch over to pure unleaded gas?

But here in the US we've used unleaded gas for a while. In fact my 380 says unleaded gas only...so if it's federal (I know it's not californian) why should the spark plugs only have half the life of a non federal? Richard

Uh, yeah.

Lead just happened to be the cheapest crap they could find to boost the octane of the fuel. Higher octane unleaded fuel will burn much cleaner than leaded fuel.

In the case of 1985 MB 380SE I doubt if there are two different engines with different compression rates. I suppose they have the same compression (Fed and non-Fed versions).

Lead was replased with MTBE some 10 years ago. MTBE raises gasoline octane value as lead did before.

Reg: Harri

So is "Federal" something european (FRG?) or is it a US thing? Now I'm really confused!

I thought federal was the US version not for california.

Not sure though. Marty

Federal means "49 state version". California had stricter standards for emissions.

Some MB's were "50 state" cars and did not have a Ca. version; they all met Ca specs.

Right on target....My 1992 190E 2.6 is a "FEDERAL" originally sold in the Midwest. It does however meet Cal. emission standards. The only difference that I am aware of is that it does not have the Check Engine light diagnostic feature. Peter

MTBE is an oxygenate and does not raise the octane. It is also poisonous crap that does more harm than good. It also displaces the fuel giving you less miles per gallon. A colossal fraud.

Which will cost billions in future when trying to clean it up out of ground where it has leaked just about everywhere. Man we are megastupid sometimes...

Most federal versions had flags attached to the upper part of each front fender.