View Full Version : Recommended Oil

06-23-2006, 03:49 PM
Has anyone noticed that Ford is recommending 5-50 Motorcraft synthetic oil for the new GT 500........as opposed to the 5-20 Motorcraft synthetic blend they recommended for the 2003/2004 Cobra. Can anyone venture a guess as to why? Should we go to 5-50 in our 03/04 engines? I am about to change my oil.......using 5-20 Castrol full synthetic and a K&N oil filter. Should I consider 5-50 instead? Has anyone used the K&N filter with poor results? Lastly, I notice a lot of you swear by Royal Purple. Why?

06-23-2006, 05:22 PM
There has been a lot of discussion on this if you look into the search on the 03/04's, after a couple of readings through here I went to 5-30 and really liked it, a lot less upper chattering towards the end of the time to change again, I would like to hear some others on this too because that was something similar if what I have been thinking of going to. Good to know that about the GT500 thanks.

06-24-2006, 08:27 PM
I also run 5w30 Mobile One synthetic in my 03. I have done a pulley change, headers, etc. and change the oil one time per year. To date there are only 12000 miles on the car. I really don't notice any chattering or engine noise with this oil weight and it is always still in the full area on the dipstick when I change. They say the heavier oil reduces horsepower, but I never noticed a difference when I first changed the oil.

06-25-2006, 09:11 AM
I have used 10w-30 (royal purple) most of the time. When ever I have used a thinner weight oil it winds up in the intake. With the multi grade oils, only consider the last number since that will be the flow characteristic once it heats up to operating temperature. I have used AMSOIL series 2000 racing 20w-50 with good results which pours like a very thin oil (unlike some other brands in the same weight category). You can also mix viscosity and use the higher weight oil as a thickening agent. There is something to say about some oils, is cling time.... The longer the cling time the more protection you have but also will cling to the crank shaft too. I have had better ET's when using the royal purple 10w-30 than with the AMSOIL 20w-50. Both are more expensive than your typical motor oil. I have not used the K&N filter since I was told it would increase oil pressure due to the amount of filtration it provides. I basically use the Mobil 1 filters. I will not swear by royal purple, it is just a better alternative than other oils. I do like the AMSOIL products as well as royal purple. Have not tried red line oil yet.

06-25-2006, 02:42 PM
i have tried all the synthetics and now use only royal purple 5w20 with k & n filter. i drive about 2k to 3k's a month and change every 7500 miles. it is expensive but for the peace of mind, and performance, it is well worth the price. the tuner that did my pulley change and tune stated that he had actually dyno'd a car before he put in royal purple and after he gained 9 horsepower. who knows......the biggest thing is to be consistant......life blood you know.....

06-28-2006, 07:53 PM
Very interesting! Maybe the tolerances are a bit different? I have been running Mobil 1 Full Synthetic 5W-30. I have used this oil in all of my cobras and stangs!

07-03-2006, 04:33 PM
I wish I knew the answer to this. It comes up regularly. It is interesting to know the new blown 5.4 is using 5/50. I would just make one consideration, the most important one over power and all else. If you use heavier oil than "recommended," make sure you're getting the appropriate lubrication. I had spoken to Ford service guys about oil weight. Of course, you always get "what ever is recommended in your manual" is what you should use. That said, I just stick with 5/20 (Castrol Synthetic).

In the end, the proper weight always seems an elusive answer, but make sure you're not chocking off the engine with a heavy weight. I would not think 5/50 would be a wise change for the Terminator's engine oil.

07-04-2006, 12:08 PM
One thing to note about motor oils. Multigrade oils intended for all season such as 5w-20 indicate how the oil will flow at certain temperatures. The W in the number indicates the oil characteristic at low temperature (not quite sure at the specified temperature it is for the viscosity for the W designation). The last number or in this case - 20 indicates the viscosity once the oil reaches operating temperature. Basically once the oil is at a high temperature it will have characteristics of a 20 weight motor oil. Viscosity is resistance to flow. You do not want your oil staying thin when at operating temperature since this will not provide a suitable oil bearing on the crankshaft. Not all oils will have the same characteristics. Case in point is the AMSOIL 20w-50 which is not like other oils that I have seen in the same category. It is relatively thin like a 5w-20 but what classifies it as a 20w-50 is the long cling time characteristic where as some if not most oils with a thin viscosity typically flush down to the pan immediatly after the motor shuts off. Since I have been using Royal Purple 10w-30 (the 5w-20 is harder to find) I bought a quart of 20w-50 to top off the oil level. It is definately not like the AMSOIL since it is relatively thick compared to the series 2000 racing oil from AMSOIL. When selecting a motor oil, use good judgement. Best to stick with what you are familiar with and not to change viscosities too often. Also to consider is change in oil pressure with different grades of oil as well as use of high filtration filters. If you notice the oil pressure increasing, chances are that the filter or oil would be too much for the oil pump or that there is too much filtration and not enough oil flow. Keep in mind that the oil is intended to suspend the fine contaminants that the filter will not remove. The main reason why one should frequently change oil is that fuel and combustion byproducts will eventually wind up in the oil. Perhaps the 5w-50 oil that ford put into the 5.4L gt and gt500 is for the increased oil seal on the pistons.