synthetic oil in older truck

[supermario2004]

so i've read about the greatness of synthetic but what about switching over on a car that already has a lot of miles. If an engine has a lot of miles on it wouldn't the vavles , gaskets, piston rings, etc be loose or warn by this point, the engine is used and warn in with that black thick goo that is reg oil. should I bother switching? is there a rule of thumb?


this is brought to my attention because I have a 77 toyota pickup that I bought cheap and spent a little less than what I bought it on smogging it and a carb. the truck is a little 2wd 5spd and has no acceleration. the body is all dinged and beat but it gets me from point a to point b. I don't know how many miles are on the engine but I bought it because it gets good gas mileage.

it has a 20r and when I bought it I gave it a tune up and drove it from my home town to arcata (humbolt co, california) which was about a long 6.5 hour drive for me. so if the truck survived that both way it can survive anything

on that trip, the best mileage I got was about 28mpg(10w-30.) fast forward to now and my recent oil change. I put it off and my mileage was steadily decreasing (about 15mpg) so I figured that the truck was just going sour and it was its time to go.

after the oil change (10w-40) and a tank of gas, I calculated that I went 200 miles ong 8 gallons of gas (about 25mpg) Yes! i was excited and glad to know that my truck wasn't dying.

i guess that reg oil gunks the engine up after about 4000 miles(i went a little more than 5k miles)

so would a switch to synthetic be worth it? can I switch over? any recomendations?(aside from getting a ford, I have a falcon)

this is my daily driver and fuel saver don't want to put any more money into it unless it helps my gas mileage.


thanks, sorry this is long,

Mario

[reb]

Sounds strange that changing the oil could make such a difference in gas mileage. Is it possible that there might be some other factors? I have noticed no changes in gas mileage related to oil changes, and I monitor my mileage with every tankful. For what it is worth, I don't think use of synthetic oil makes economic sense for my purposes.

As for the economics of changing, I think you are on the right track. You should consider the cost difference over time (the cost of regular oil, changed every x miles vs the cost of synthetic, changed every y miles and any true diffference in fuel costs between the two types).

[390FE]

As long as the motor is not leaking oil I would not worry about changing over to synthetic. Synthetics are able to be mixed with regular oil if you want to do that.

I am using 0W30 Amsoil in my 2001 Focus(soon to be in the toyota once I get it running) and up till then I was getting 25-28mpg not able to get over 28mpg on a good day(tank). After switching over I now get 28mpg average and 30+ on a good day(tank). I need to learn to keep my foot out of it . I now need to change my oil because I am now getting about 22mpg but I only drive under 2 miles and 10-15 minutes(danm traffic lights) to work and never get over 30mph in city traffic when I do move.

If your in CA and it doesn't get to cold(not sure what part your in) I'd say get a thinner oil and the engine won't work as hard and give you better milage.

It seems people on this board like to use Mobil1 which is a good synthetic also.

[Mushroom_Toy]

I recently switched out my oil to synthetic at 210,000 miles. It's not something that has to be done, but I do say it was worth it. Engine noise overall has gone down, which I believe is the oil reducing friction better. Also I believe I got a tiny hp increase too. Overall I think it was a good investment.

[karugs]

Synthetic oils have more regular molecules that can seep into small cracks that regular dino oil, which has larger and more irregular molecules, can't, hence the leaks when switching to synthetic. There will be a marked difference. However some have warned that if you switch to synthetic, that might cause alot more troubles than you already have (or don't). If I were you I'd just change the oil hot and change it often like you used to. Consider it cheap insurance. Back in 1977 they recommend dino oil, so it's proven that dino oil is best for your truck. Also, if you know the exact condition of your engine seals, you'd have no problem switching over.

The mileage difference can be attributed to your truck's performance. I change my oil every 3000 miles on my '83 300D, give or take some miles.

Make sure you also use the correct weight of oil, which varies with usage and temperature. Best of luck!