Hello all,

I am uncertain of what type of oil to put in my 1989 Mercury Grand Marquis and how much. I have read that some people put in all different kinds of oils and different additives/blends to help the engine, make it run smoother. My Marquis has 43,000 miles on the 5.0L engine. What oils should I use during the summer and winter and how much?

Thanks,

OSDCrusher

 

if you have the owners manual, it specifies 10w-30... i use 10w-40 year round in my cars... i prefer thicker oil though since cars are old and have a few leaks... i have done my valve covers and stuff, but dont like fighting the oil pan gaskets and lower intake... i prefer valvoline and never use pennzoil or castrol since they leave residue on stuff like a wax buildup on parts gumming stuff up... to clean system, use some trans fluid like a quart when oil gets low enough and run that for a couple hundred miles to clean the system and break gunk down... trans fluid is full of cleaners and additives that will help clean the engine then do an oil change... no matter what the oil dipstick says, the car takes 5 quarts of oil... i buy 6... i drain and pull filter, than plug the pan back up and dump the extra quart in... give it a couple minutes than pull drain plugs out... yes plugs, there are 2 ... one facing forward and one facing straight down... do 1 plug at a time... after draining the "flush quart" out, put plugs in and add your 5 quarts and add filter... it helps to turn the steering wheel to the left since steering stuff is in the way of oil filter and turning wheels makes it easier

 

Wow. Thank you for the response. I have heard about the 2 drain plugs on these cars. I would like to replace them both so they never leak. Do you know if this drain plug fit the car? Does it matter which one you remove first? Also, when you put in your "flush quart" of oil, are you putting it in with no oil filter on? And what is the purpose of this "flush quart"? Should I run 10W40 in my Marquis even though the engine only has 40,000 miles on it? It doesn't burn oil (that I can tell) and it runs smooth with 10W30 in the summer.

Thank you very much

 

flush quart is to get and extra gunk out of system along with pan and dont matter if the filter is on or off... if car is fine, 10w-30 will be fine... the drain plugs you linked look like the right ones... biggest things with doing oil changes is to change the gaskets...

 

Oh I understand now. Thank you for all of your help, 87_Crown_Vic. So I will use 10W30 in the Marquis. Next question is, what brand of oil, and what brand of filter? I was going to get a Motorcraft filter and Valvoline synthetic. What do you recommend?

 

i wouldnt suggest using full synthetic... i would go with a gradual change to synthetic... by like 1 or 2 quarts of synthetic and rest regular... going right to synthetic can cause trouble in an older vehicle where seals and gaskets may have dried and can leak... synthetic contains smaller molecules and will find small leak areas ... purolator and the motorcraft filters are comparable... just like when you do a new engine rebuild, using straight synthetic will never let the engine break in because the oil doesnt let the parts learn where to go i guess you can say...

 

oh... forgot to mention... when done with oil change, take car around the block and check oil... wherever oil is at on dipstick after letting car sit a few minutes off, mark dipstick where your full mark is so you know where it belongs at full

 

Okay I got it. Couldn't I also buy a synthetic blend oil instead of buying some regular oil, and some synthetic? OR should I just keep using regular oil?

 

using synthetic blend would make the mix pretty much a 50/50 mix... you can try it and see what happens... myself, i dont like a low miled older vehicle... it means the seals and gaskets have chance to dry out and leak along with cylinder walls of engine being able to rust or the piston rings getting froze up on the pistons and not letting them adjust to cylinder walls to seal right... but that is my opinion...

 

I see what you mean. That is very true. I'm still at a dead end and don't know what to do lol