Alright so im due for my first oil change in my 99' 4.6 and usually I use Castrol GTX as my oil of choice, but here its starting to get down to the single digits and even below zero in the morning so it gets pretty cold, and my truck seems to have a tough time starting when its cold. sometimes itll take a good 4-5 seconds of crannking b4 itll turn over and even somedays itll start up and die a few times and i have to keep my foot on the accelerator to keep it alive. so more trouble than it should be. Im gonna change the plugs and seafoam it this weekend, but i was thinking would a synthetic oil or part synthetic oil help it out? The only downside is that the manual said not to use synthetics in it, i dont know why, so any info would be great. thanks

 

Personally I think its over Rated!!! Just change your oil as required.

 

My mechanic friends told me that synthetic oil caused all the seals to leak.
That was 15 years ago, so maybe the newer stuff is different.

 

Buahahahahaahhaa. Look on the bottle of Motorcraft oil 'RECOMMENDED' for your truck! Guess what. Synthetic BLEND...

The only thing overrated about synthetic is Mobil 1. That **** is overpriced when you can get the same thing cheaper in another brand.

Completely NOT the truth.


To the OP.

Your truck is a DOHC or SOHC modular motor. DESIGNED to run 5-20 motor oil...from the Motorcraft brand...which is IN FACT synthetic blend...full synthetic or not...won't help your cold start problem. Look at what the numbers mean in the oil you are buying.

Hell most think the 'W' in 5w-20 means 'weight'...it doesn't. It means WINTER....The lower the number, the lower the viscosity of the oil. Oils have two the viscosity ratings...cold and hot. The first number is cold, the second is warm/operating temp. Hence the reason for the higher number. Who would want an oil that provides more protection cold, than when the motor is warm. Plus with a lower viscosity oil when cold...it starts better, the starter doesn't have to push through the 'maple syrup' when cold.


Bottom line, if you want your truck to start better in the winter, get a 0-20 oil...synthetic or blend...

How cold is it getting where you are? Flash point of gasoline change as well when its cold...that combined with cold air and less spark will play a role...might be the nature of the beast..

Good luck sir.

 

I switched my truck over to full synthetic after I bought it, and I noticed a big difference. I used high mileage mobil 1, because my truck has 166k on it. I was worried about it causing leaks, but I havent had a single problem, not even seepage. People can say it overpriced but I have only heard great things about mobil 1, I have even heard that it helps with the piston slap problem that some of the 5.4 motors have.

 

The only thing I've heard about synthetic oil is that it's too slippery to break in an engine and the piston and rings won't seat, but after an engine is broken in synthetic is the way to go.

 

Ive been using castrol syntec 20-50 and a premium filter for all 138k miles for the life of my 5.4l 4x4 scab. Used to pull a 7k plus but and trailer. It gets real hot in the summer down here. Definately no leaks or seepage. It seems to be doing good for me. Yes it costs more but good oil and filter is cheaper than a three or four hundred dollar a month payment on a new truck.

 

Try an oil pan heater. As soon as I get some time thats what I'm gonna do combined with a block heater. Easier starts and less warm up time